Eucrites


Eucrites are the E class of the HED achondrite clan (howardite-eucrite-diogenite). The HED clan of meteorites represents volcanic rocks (surface flows) and plutonic rocks (deeper crystallization) formed from basaltic magmas. Eucrites, from the Greek word eukritos, meaning "easily distinguished," are probably more similar to terrestrial rocks than any other asteroidal meteorite class. Like terrestrial basalts, eucrites formed by partial melting of parent rocks and are typically extrusive (surface flows). They are also referred to as "basaltic achondrites" because of their similarity to terrestrial basalts in texture and gross mineralogy, but differ in bulk composition and other characteristics. For example, they contain reduced, metallic nickel-iron (Ni-Fe) instead of oxidized iron minerals, e.g., magnetite (Fe3O4).

Fractured surface of the North African DaG 647 eucrite. Buff and dark grains are pyroxenes, cream is plagioclase. Height of the photograph is about 6 cm. Image © 2005 T. E. Bunch

Eucrites are composed of orthopyroxene, pigeonite, Ca-rich pyroxenes and plagioclase with minor amounts of chromite, ilmenite, troilite and Ni-Fe metal. A few eucrites, e.g., Moore County are similar to terrestrial gabbros (plutonic rocks) in having cumulate textures (preferred orientation of major minerals) that indicate crystal layering by settling-out in a magma chamber, analogous to the accumulation of fallen tree leaves into layered piles.

Textural similarity of the basaltic eucrite Stannern (left; pyroxenes white to gray; pyroxene, brown to buff) compared with a terrestrial basalt (right; same with highly colored olivine grains). Image © 2005 T. E. Bunch.

Example of a subophitic eucrite basalt with augite partially enclosed by plagioclase (white in both images; PPL, left; XPL, right). Height is 3 mm. Image © 2005 T. E. Bunch

Example of cumulate texture in the eucrite Moore Co.; plagioclase, white to gray. PPL on left, XPL on right. Height is 3 mm. Image © 2005 T. E. Bunch

Summary of Eucrite Characteristics

Basaltic eucrites are typically brecciated (monomict or polymict). Either orthopyroxene or pigeonite will be present.

Minerals and compositions:

Texture: Basaltic eucrite textures are highly variable, mostly subophitic and ophitic, but may include phyric and variolitic textures, in addition to shock-formed textures, e. g., microgranular, quench, and microphenocrystic. Cumulate eucrites are commonly protogranular with equal amounts of pyroxene and plagioclase.


Arabian Peninsula 002

United Arab Emirates
Find: 2006
Achondrite (eucrite)

Physical characteristics: A dark, 54 g completely crusted stone.
Petrography: (T. Bunch and J. Wittke, NAU). Eucrite breccia with ophitic to subophitic textures. Contains pigeonite, augite, plagioclase, FeS, metal, and SiO2. Pigeonite cores are rimmed by subcalcic augite. Pigeonite basal sections show well-developed twinning and plagioclase has extensive Carlsbad-albite twinning. Mesostasis pockets consist of fine-grained intergrowths of plagioclase, SiO2, and FeS.
Mineral compositions and geochemistry: Pigeonite cores (Fa41.4Wo8.2; FeO/MnO = 30), subcalcic augite rims (Fs46Wo21.6; FeO/MnO = 29) and plagioclase (An84.292.2).
Classification: Achondrite (eucrite); minimal shock, minimal weathering with minor carbonate/ iron oxide veins.
Type specimen: A 10.8 g sample is on deposit at NAU. The main mass holder is anonymous.

AP 002. Image width = 6 mm. Image © T. E. Bunch, 2007


Arabian Peninsula 005

United Arab Emirates
Find: 2005
Achondrite (eucrite, monomict breccia)

Physical characteristics: A brownish 146 g stone, with no fusion crust, partially desert-etched by sandblasting.
Petrography: (J. Wittke and T. Bunch, NAU) Porphyroclastic texture of relict cumulate basalt clasts surrounded by a fine-grained matrix of recrystallized basalt. Thin, shock-melt veins transcend the sample. Prominent iron oxide staining surrounds metal grains.
Mineral characteristics and geochemistry: Pigeonite (Fs52.5Wo8.7; FeO/MnO = 33), augite (Fs42.8Wo27.2), chromite (Cr/[Cr + Al] = 0.75), and plagioclase (An90.5).
Classification: Achondrite (eucrite, monomict breccia); moderate shock and weathering.
Type specimen: A 21 g sample is on deposit at NAU. The main mass holder is anonymous.


Arabian Peninsula 006

United Arab Emirates
Find: 2005
Achondrite (eucrite, monomict breccia)

Physical characteristics: A 67 g stone that has somewhat weathered fusion crust and desert staining.
Petrography: (J. Wittke and T. Bunch, NAU) A fine-grained, eucrite monomict breccia. Ophitic- to subophitic-textured, plagioclase contains numerous, tiny (<0.02 mm) oriented euhedral pyroxene crystals. Has a moderate degree of undulatory extinction in plagioclase and pyroxenes. Contains orthopyroxene, pigeonite, augite, plagioclase, ilmenite, chromite, FeS, and metal.
Mineral compositions and geochemistry: Orthopyroxene host (Fs56.6Wo2.2; FeO/MnO = 29), augite exsolution lamellae (Fs28.8Wo43.6), pigeonite (Fs52Wo8.7; FeO/MnO = 33), and chromite (Cr[Cr + Al] = 0.84).
Classification: Achondrite (eucrite, monomict breccia); minimal shock and weathering.
Type specimen: A 13.5 g sample is on deposit at NAU. The main mass holder is anonymous.


Dhofar 1429 (18°32'16"N 54°11'16"E)

Oman
Find: March 2006
Achondrite (eucrite, monomict breccia)

History and physical description: An 89 g stone that is covered with very fresh fusion crust, was found in the Dhofar region of Oman by R. Ward 0n March 5, 2006.
Petrography (T. Bunch and J. Wittke, NAU): partially recrystallized monomict breccia. Relict textures include fine-grained subophitic transitional to variolitic. The matrix is a mixture of finely comminuted to recrystallized zones. Narrow shock veins transect the specimen and plagioclase, in relict basalt clasts, is partially converted to maskelynite.
Mineral compositions and geochemistry: Relict basalt clasts: orthopyroxene (Fs60.3Wo2.2, FeO/MnO = 32), pigeonite (Fs51.2Wo12.3, FeO/MnO = 30), augite (Fs25Wo45.3), chromite (Cr/[Cr+Al] = 0.81) and metal (Ni = 0.27 wt%).
Classification: achondrite (eucrite, monomict breccia). Weathering grade is extremely low and the shock level has a range of medium to high.
Type specimen: A sample of 18.8 g is on deposit at NAU. R. Ward holds the main mass.


Northwest Africa 1181

Morocco
Found 2001
Achondrite (polymict eucrite)

NWA 1181. Image © T. E. Bunch, 2004

A 3279 g, crusted stone was purchased in Rissani, in 2001. Classification and mineralogy (T. Bunch and J. Wittke, NAU): modal analyses (area of 34 cm2), eucritic basalts 94 vol%; shock melt clasts, 4 vol%, diogenites 2 vol%. At least 34 different eucrite clasts were observed that range from micro-ophitic/subophitic (<0.1 mm) to cumulate to very-coarse grained gabbroic (3-7 mm). Gabbro pyroxenes are predominantly 2-5 mm in size subcalcic ferroaugites (TiO2 = 0.9 to 2.1 wt%) with 3-6 mm plagioclase, An92; ilmenite, chromite (Al2O3 = 9.2 wt%), and acicular crystals of tridymite up to 7 mm in length. Shock stage, S2; weathering grade, variable, W1 to W2. Specimens: type specimen, 18.4 g and three thin sections, NAU; main mass is with the purchaser.


Northwest Africa 1835

Morocco
Found 2002
Achondrite (cumulate eucrite, polymict)

NWA 1835 Image © T. E. Bunch, 2004

A 28.84 g stone was purchased in Rissani, Morocco in 2003. Classification and mineralogy (T. Bunch and J. Wittke, NAU): polymict cumulate eucrite that contains a variety of shocked clasts (shock level, S3-S5). Low-Ca pyroxenes range from Fs42Wo3.4 to Fs52.4Wo12.2; plagioclase, An92.1-94.4; minor ilmenite, chromite, sulfides, and silica. Several cumulate pigeonites contain melt inclusions (0.024 to 0.065 mm diameter) of micron to submicron pyroxenes, plagioclase, and glass. Defocused microbeam analyses indicate bulk compositions similar to those suggested by Treiman (1997) to represent eucrite parent magmas. Very fresh crust and interior. Specimens: 5.7 g, NAU; main mass, Oakes.

NWA 1835. (left) Unshocked cumulate clast in plane polarized light. (right) Pyroxene (red/yellow), plagioclase (gray) in crossed polarized light. Base width = 5 mm. © T. E. Bunch, 2004

NWA 1835. (left) Intense fragmentation (brecciation) in plane polarized light (right) Pyroxene (purple/pink), plagioclase (gray) in crossed polarized light. Base width = 5 mm. Image © T. E. Bunch, 2004

NWA 1835. (left) Partially shock-melted and granulated cumulate basalt in plane light. Smaller included remnant clast is less shocked. Cross-cutting veins are terrestrial carbonate. (right) Crossed polarized light emphasizes the shock-induced reduction in birefringence and prominent undulatory extinction, which are caused by disordering of the crystal structure. Image © T. E. Bunch, 2004


Northwest Africa 1836

Morocco
Found 2002
Achondrite (cumulate eucrite, monomict)

NWA 1836. Image © T. E. Bunch, 2004

A 1102 g partially crusted, single stone was purchased in Rissani, Morocco in 2003. Classification and mineralogy (T. Bunch and J. Wittke, NAU): highly contorted mass of eucrite clasts with cataclastic mantles that are in turn covered by partially melted to recrystallized masses. Cumulate texture with subophitic enclaves. Clast orthopyroxene, Fs56.4-59Wo2.5-4; exsolution lamellae, Fs43.4-46.3Wo23-25.6; recrystallized zone, Fs54.5-57.5Wo8.4-13.5. Chromite, Cr/(Cr + Al) = 0.85, TiO2 = 14.6 wt% with exsolution lamellae of ilmenite; plagioclase, An91-93.6. Shock level, S1 to S5. Very fresh. Specimens, 25.5 g, NAU; main mass, Oakes.

NWA 1836. (left) Fine-grained crushed zone ("pinched") in plane light. Glassy matrix separates two less shocked areas. (right) Crossed polarized light reveals the severe damage; black regions are glass. Base width = 5 mm. Image © T.E. Bunch, 2004

NWA 1836. (left) Moving from left to right across a severely deformed zone (plane polarized light): lightly shocked cumulate basalt (far left), off-set fault block that contains flow elongation and recrystallization of plagioclase and pyroxene; melt pockets and veins. (right) Crossed polarized light shows the severe damage; glass is black. Base width = 5 mm. Image © T. E. Bunch, 2004


Northwest Africa 1908

Morocco
Found 2001
Achondrite (eucrite, cumulate)

NWA 1908. Image © T. E. Bunch, 2004

A 980 g, complete and very fresh stone was purchased in Rissani, January 2002. Classification and mineralogy (T. Bunch and J. Wittke, NAU): monomict, orthocumulate eucrite breccia. Contains cumulate, unzoned plagioclase An89-90 (N=24); orthopyroxene with tight compositional cluster at Fs65Wo2 (N=36) and exsolution lamellae of augite, Fs28Wo44; minor TiO2-rich (18.2 wt%) to TiO2-poor (<3 wt%) chromite is present as inclusions in pyroxene. Microbreccia shear zones and plastic deformation of adjoining minerals with melt pockets are common within clasts. Non-sheared clasts are S1. Specimens: type specimen, 20.6 g, NAU; main mass, Farmer.

NWA 1908. (left) Cumulate texture (plane polarized light) produced by the simultaneous crystallization of pyroxenes (brown) and plagioclase (white) and crystal settling in the magma fluid. (right) Plagioclase is gray in ); base width = 5 mm. Image © T. E. Bunch, 2004.

NWA 1908. (left) Shear damage with formation of melt glass from frictional heating (dark areas in plane polarized light). (right) Plagioclase is gray in crossed polarized light. Base width = 3 mm. Image © T. E. Bunch, 2004.


Northwest Africa 1909

Morocco
Found 2001
Achondrite (eucrite, monomict)

NWA 1909. Image © T. E. Bunch, 2004

A 1.2 kg, complete and very fresh stone was purchased in Rissani, January 2002. Classification and mineralogy (T. Bunch and J. Wittke, NAU): monomict breccia with subophitic to microgabbroic clasts of zoned plagioclase (cores: An91; rims: An80Or1), zoned pigeonite (cores: Fs37Wo7; rims: Fs53Wo11) and zoned subcalcic ferroaugite (cores: Fs47Wo20; Rims: Fs49Wo24). Minor phases include ilmenite, chromite, silica, and pyrrhotite. Inclusions of granular Fe-rich olivine (Fo81) and metal (0.31 wt% Ni; 1.4 wt% Co) are present in pigeonite. Specimens: type specimen, 20.9 g, NAU; main mass, Farmer.

NWA 1909. (left): Breccia clast with cumulate texture in plane polarized light: plagioclase (white), pyroxene (brown). The long directions of pyroxene and plagioclase crystals tend to align parallel to an east-west direction; preferred orientation by crystal settling and/or flow. (right) Prominent twinning in pyroxene (yellows) and plagioclase (grey) is revealed in crossed polarized light. Base width = 4.5 mm. Image © T. E. Bunch, 2004.


Northwest Africa 1925

Morocco
Found 2001
Achondrite (eucrite)

NWA 1925. Image source: http://www.meteoriteguy.com/nwa1925.htm

A single, 86 g, complete stone was purchased in Tagounite in 2002 April. Classification and mineralogy (T. Bunch and J. Wittke, NAU): gabbroic, cumulate eucrite; tabular crystals of plagioclase (<4 mm in longest dimension) poikilitically enclosed by large pyroxenes (up to 8 mm). Plagioclase is An91 with melt inclusions of a silica polymorph, Mg-augite, and ilmenite. Complex pyroxenes consist of inverted pigeonite (Fs52.5Wo4.2) with broad (5-8 µm) augite exsolution lamellae (Fs25Wo41) parallel to (100) of host orthopyroxene and blebs of augite that exsolved prior to or during pigeonite inversion. In addition, relic patches of pigeonite contain fine augite lamellae parallel to (001). Chromite, Cr/[Cr+Al] = 63-73, pyrrhotite, and tiny inclusions of orthopyroxene in Ni-poor metal (Ni = 0.48 wt%; Co = 2.28 wt%) are also present. No ilmenite or silica was found outside of melt inclusions. Shock level, S2/3; weathering grade, W1. Specimens: type specimen, 17.2 g, NAU; main mass, Farmer.


Northwest Africa 1980

Morocco
Found 2002
Achondrite (eucrite)

NWA 1980. Image © T. E. Bunch, 2004

A 546 g fully crusted stone was purchased in Erfoud in 2002. Classification and mineralogy (T. Bunch & J. Wittke, NAU): monomict, cumulate eucrite breccia; clast size, millimeters to 6 cm; cataclastic, microgranular veining with minor recrystallization. Inverted pigeonite (Fs48Wo2.5); augite lamellae (Fs15Wo46); plagioclase (An93); sulfide, ilmenite, chromite (Cr/[Cr+Al] = 65), and metal (Ni = 7.1 wt%). Shock level, S3/4; reduced birefringence, mosaicness, and deformation lamellae in pyroxenes; minor development of maskelynite. Very fresh, shiny black fusion crust and un-oxidized metal; minor terrestrial carbonate alteration veins. Specimens: 23 g, NAU; main mass, Boswell.

NWA 1980. (left) Large clast at right has attached shock-melt, partially crystallized breccia (dark) in plane polarized light. NE-SW trending, discontinuous vein or melt pocket is shock-melted glass. NW-SE trending vein is fracture filling of terrestrial carbonate. (right) Plagioclase is gray in crossed polarized light. Base width = 5 mm. Image © T. E. Bunch, 2004


Northwest Africa 1981

Morroco
Found 2002
Achondrite (polymict eucrite)

NWA 1981. Image © T. E. Bunch, 2004

A 197 g complete and crusted stone was purchased in Erfoud, Morocco in 2003. Classification and mineralogy (T. Bunch and J. Wittke, NAU): unique, highly shocked (S5) polymict breccia. Flow orientation of partially granulated clasts; elongated melt pockets with fine-grain crystallites of plagioclase, pyroxenes, and silica, and minor remnant glass. Pyroxenes: extensive development of planar deformation features and fractures, reduced birefringence, and minor recrystallization; presence of maskelynite. Eucrite clasts: 82 vol% are cumulate, 18 % are basaltic. Cumulate pyroxenes: orthopyroxene mean = Fs49Wo13, FeO/MnO = 27.4; exsolved augite, Fs15Wo44; pigeonite mean = Fs42 Wo13, FeO/MnO = 29.3; anorthite range, An70.3-92.8. Minor ilmenite, sulfides, phosphate, and silica polymorph. Very fresh, no apparent iron staining. Specimens: 21.3 g, NAU; main mass, Boswell.


Northwest Africa 2049

Morocco
Found 2003
Achondrite (eucrite, cumulate)

NWA 2049. Image © T. E. Bunch, 2004

A 69.15 g, nearly complete stone, was purchased in Rissani, Morocco, September 2003. Classification and mineralogy (J. Wittke and T. Bunch, NAU): remarkably fresh cumulate eucrite with minor recrystallization. Textural characteristics similar to Moore County, grains size < 3 mm with cumulate plagioclase. Pigeonite = Fs56.5Wo8.5; ferroaugite = Fs31Wo40. Plagioclase is An88 and chromite Cr/[Cr+Al] = 0.85. Minor ilmenite and troilite. No evident shock characteristics. Specimens: 15.1, NAU; main mass, Farmer.

NWA 2049. (left) Cumulate texture in plane light: plagioclase (white) with pigeonite and augite pyroxenes and ilmenite. (right) Crossed polarized light reveals twinned plagioclase (white/grey). Base width = 5 mm. Image © T. E. Bunch, 2004


Northwest Africa 2050

Morocco
Found 2003
Achondrite (eucrite, basaltic)

NWA 2050. Image © T. E. Bunch, 2004

A 33 g complete stone was purchased in Rissani, Morocco, September 2003. Classification and mineralogy (J. Wittke and T. Bunch, NAU): unbrecciated subophitic eucrite; fine grain size (<one mm). Shock decorated plagioclase and pyroxene; shock veins transcend the entire sample; shock level, S3. Pigeonite, Fs54Wo8; augite, Fs31Wo42.6; plagioclase. An91.3. Rare metal, Ni = 0.23; Co = 0.21; minor ilmenite, troilite, and silica. Light oxidation and staining. Specimens: 6.5 g, NAU; main mass, Farmer.


Northwest Africa 2051

Morocco
Found 2003
Achondrite (eucrite, polymict)

NWA 2051. Image © T. E. Bunch, 2004

A 125.2 g complete stone was purchased in Rissanni, September 2003. Classification and mineralogy (T. Bunch and J. Wittke, NAU): Polymict eucrite; modes in vol%: cumulate eucrite, 74, basaltic eucrite, 17, diogenite 6, shock clasts, 3. Cumulate eucrite orthopyroxene, Fs46.7-54.7Wo2-3.1; augite, Fs38.4-44Wo20-24.4; plagioclase, An89.4. Minor metal (Ni = 0.57 wt%; Co = 0.42), ilmenite, chromite, troilite and silica. Shock level, S2; minor weathering. Specimens: 20.7 g, NAU; main mass, Farmer.

NWA 2051. (left) Clast of cumulate plagioclase and pyroxenes set in fine-grained cataclastic matrix in plane polarized light. (right) Poikiolitic texture seen in crossed polarized light - single crystal of plagioclase (gray) encloses smaller pyroxene crystals (inclusions), indicating that pyroxenes crystallized first. Base width = 5 mm. Image © T. E. Bunch, 2004


Northwest Africa 2054

Morocco
Found 2003
Achondrite (eucrite, polymict cumulate)

A 45.8 g complete stone was purchased in Rissani, Morocco, September 2003. Classification and mineralogy (T. Bunch and J. Wittke, NAU): hand specimen is medium to very dark gray; highly shocked (to S6), polymict cumulate eucrite; maskelynite, recrystallized plagioclase and pyroxenes, crystallized melt pockets. Orthopyroxene (avg.), Fs50.7Wo3; pigeonite, Fs47.5Wo10.2; plagioclase and maskelynite, An88.8-90.3. Minor ilmenite, sulfides, and chromite, Specimens: 5.35 g, NAU; main mass, Farmer.

NWA 2054. (left) Large, recrystallized cumulate clast at top (pyroxenes are brown) and smaller, ophitic and subophitic clasts scattered throughout clastic matrix are observed in plane polarized light. (right) Pyroxenes have bright colors and plagioclase is gray in crossed polarized light. Base width = 5 mm. Image © T. E. Bunch, 2004


Northwest Africa 2061

Morocco
Found 2003
Achondrite (eucrite)

NWA 2061. Image © T. E. Bunch, 2004

A 135 g very fresh and fully crusted complete stone was purchased in Erfoud, July 2003. Classification and mineralogy (T. Bunch and J. Wittke, NAU): unbrecciated, porphyritic basalt with long (up to 9 mm) phenocrysts of low-Ca pyroxenes set in a matrix of smaller pyroxenes and blocky to acicular plagioclase. Clots (3 to 8 mm in diameter) of low-Ca pyroxene phenocrysts set in radiating bundles of plagioclase (variolitic texture) are distributed throughout the specimen. Main mass, low-Ca pyroxene phenocrysts are zoned from cores of Fs29.8Wo4.9 to pigeonite rims of Fs49Wo12; Fe/Mn = 29.8 and 37.2, respectively. Small inclusions of metal (Ni = 0.05 to 0.25 wt%) are sparsely distributed. Blocky to acicular plagioclase is An83.7Or2 with a small compositional range. All plagioclase, regardless of size and morphology, contains up to 0.97 wt% FeO. Clot pyroxene cores are Fs42.9Wo28 (Fe/Mn = 35.6) and rims are Fs49.2Wo25.1 (Fe/Mn = 36.1). Very fresh with no apparent weathering; shock level, S2. Specimens: type sample, 21.7 g, NAU; main mass, Boswell.

NWA 2061. (left) Typical host texture in plane polarized light. (right) Pyroxene phenocrysts show FeO-enriched margins relative to their more magnesian cores (compositional zoning shown by color variations: yellow to red-brown). Margin compositions are similar to those of the smaller FeO-rich matrix pyroxenes. Some pyroxenes show prominent optical twinning. Base width = 2.5 mm. Image © T. E. Bunch 2004.

NWA 2061. (left) Clot (magmatic segregation) of porphyritic texture with large pyroxene phenocrysts (much larger grains) in a variolitic (divergent growth) plagioclase matrix in plane polarized light. (right) Crossed polarized light. Base width = 2.5 mm. Image © T. E. Bunch 2004.


Northwest Africa 2062

Morocco
Found 2003
Achondrite (eucrite)

NWA 2062. Image © T. E. Bunch, 2004

A 50.3 g partial stone with 20 % crust was purchased in Erfoud, July 2003. Classification and mineralogy (J. Wittke and T. Bunch, NAU): fine-grained subophitic to intergranular basalt with recrystallized, cataclastic enclaves and thin, shock-melt veins. A swirling flow pattern of solidifying magma is evident. Orthopyroxene compositions are tightly clustered around Fs63.1Wo2.1 (Fe/Mn = 32.7); Ca-rich pyroxene centered about Fs25.2Wo48.1. Plagioclase, An91.3. Minor phases include silica, ilmenite, chromite, low Ni-metal, and phosphate. Weathering grade, W1: exterior iron oxides and caliché; slight interior staining. Shock level is variable from S2-S4. Specimens: 13.8 g, NAU; main mass, Boswell.

NWA 2062. Image © T. E. Bunch, 2004


Northwest Africa 2063

Morocco
Found 2003
Achondrite (eucrite, monomict)

NWA 2063. Image © T. E. Bunch, 2004

A 95.8 g partial stone with 50 % crust was purchased in Erfoud, July 2003. Classification and mineralogy (J. Wittke and T. Bunch, NAU): Coarse grained variolitic to subophitic with sparse, large (2-4 mm) orthopyroxene phenocrysts; small (< 1-3 mm) enclaves of fine-grained variolitic texture without phenocrysts; lightly brecciated with minor recrystallization. Opx phenocrysts, Fs58.5Wo2 (Fe/Mn = 29.6-32.8); matrix augite, Fs24.8Wo3.6; plagioclase, An81.7Or5. Minor chromite, ilmenite and silica. Incipient maskelynite, planar fractures, mosaicness, and reduced birefringence in pyroxenes; shock level, S3/4. Interior very fresh, Specimens, type sample, 20.8 g NAU; main mass, Boswell.

NWA 2063. Image © T. E. Bunch, 2004

NWA 2063. Image © T. E. Bunch, 2004


Northwest Africa 2064

Morocco
Found 2003
Achondrite (eucrite, cumulate)

NWA 2064. Image © T. E. Bunch, 2004

A 94.4 g complete and fully crusted stone was purchased in Erfoud, July 2003. Classification and mineralogy (T. Bunch and J. Wittke, NAU): coarse-grained (< 3.2 mm) cumulate basalt; cumulate plagioclase with intercumulate pyroxene and minor ilmenite. Plagioclase, An91.8Or1; orthopyroxene, Fs49.5Wo1.8 with exsolution lamellae of Fs41.5Wo12.8; augite, Fs9.1Wo44. Subrounded, cm-size clasts set in finely crushed, unrecrystallized matrix; shock level, S1. Very fresh with no apparent weathering; shiny fusion crust. Specimens: 21.1 g, NAU; main mass, Boswell.

NWA 2064. Images © T. E. Bunch, 2004

NWA 2064. Images © T. E. Bunch, 2004


Northwest Africa 2065

Morocco
Found 2003
Achondrite (eucrite)

NWA 2065. Image © T. E. Bunch, 2004

A 58 g partial stone with 40 % crust was purchased in Erfoud, July 2003. Classification and mineralogy (T. Bunch and J. Wittke, NAU): monomict breccia of highly variable textures: fine-grained (< 1 mm) cumulate to subophitic with a partial overlay of metamorphic-granular (prominent 120° triple junctions). Cumulate areas; orthopyroxene host Fs58.2Wo2.1, exsolution lamellae, Fs25Wo45; plagioclase, An90.1, Cr/[Cr+Al] = 0.877; subophitic Ca-poor pyroxene, Fs62.3Wo5 with exsolved Fs27Wo43.9. This specimen probably sustained high shock levels, but shock indicators were mostly annealed-out during post-impact metamorphism. Very fresh, little apparent weathering. Specimens: type, 11.6 g, NAU; main mass, Boswell.

NWA 2065. Image width = 7 mm. Image © T. E. Bunch, 2007


Northwest Africa 2066

Morocco
Found 2003
Achondrite (eucrite, monomict)

NWA 2066 © T. E. Bunch, 2004

A 58.2 g complete stone with 90 % crust was purchased in Erfoud, July 2003. Classification and mineralogy (J. Wittke and T. Bunch, NAU): brecciated, medium to coarse-grained (< 3 mm) ophitic to subophitic basalt. Orthopyroxene Fs61.8Wo2.2 with exsolved augite lamellae of Fs25.4Wo45.4; plagioclase, An91.2; chromite, Cr/[Cr+Al] = 0.85 and minor ilmenite, silica, sulfide and phosphate. Minor recrystallization of shocked pyroxenes and annealing of plagioclase and pyroxenes (shock decorations); incipient maskelynite, and parallel fracturing in pyroxenes; shock level, S3/4. Dull fusion crust and minor staining. Specimens: type, 11.5 g, NAU: main mass, Boswell.

NWA 2066. (left): Lightly to moderately shocked cumulate breccia in plane polarized light. (right) Plagioclase is gray and pyroxene colored in crossed polarized light. Image width = 8 mm. Images © T. E. Bunch, 2004.


Northwest Africa 2079

Morocco
Found 2002
Achondrite (eucrite, monomict)

NWA 2079. Image © T. E. Bunch, 2004

A 496 g, partial stone with 70 % fusion crust, was purchased in Rissani, March 2002. Classification and mineralogy (T. Bunch and J. Wittke, NAU): brecciated basalt with < 15 vol% cataclastic matrix; clast grain size range, 1.5 mm to 0.4 mm; cumulate texture with strong, preferred orientation of plagioclase and pyroxene crystals in flow-like patterns in most clasts. Orthopyroxene, Fs55-61 Wo1.5-2.1; exsolution lamellae; Fs44-47Wo15-21; plagioclase more sodic than most typical eucrites; An77-82Or2.5-4.1; minor silica, ilmenite and chromite. Shock level, S3; well-developed parallel fracturing and mosaicism in pyroxenes and reduced birefringence in major minerals. Very fresh interior with greenish appearance. Specimens: 21.3 g, NAU; main mass, Moroccan Imports, Imperial Beach, CA USA.

NWA 2079. (left) Clast with strong preferred orientation by crystal settling and/or flow alignment in plane polarized light. (right) Crossed polarized light. Base width = 9 mm. Images © T. E. Bunch, 2007.


Northwest Africa 2106

Northwest Africa
Purchased 2004
Achondrite (monomict eucrite)

NWA 2106. Image © T. E. Bunch, 2004

A 322.4 g stone was purchased in Erfoud, Morocco in January 2004. Description and classification (J. Wittke and T. Bunch, NAU): a monomict breccia that is mostly composed of metabreccia clasts. Some of these clasts contain fragments of coarse-grained (between 2 and 3 mm) cumulate basalts surrounded by partially recrystallized, finer-grained pyroxenes and plagioclase of similar compositions. Large, cumulate pyroxenes typically show strong core to rim compositional zoning; cores range from Fs36.1Wo4.8 to Fs39.5 Wo7.4 with rims of ~ Fs54.8Wo14.6; plagioclase, An84.4. Shock level, S1-2; many shock features were apparently annealed out during post-shock metamorphism. Specimens: 22.8 g, NAU; main mass, Farmer.

NWA 2106. Images © T. E. Bunch, 2004

NWA 2106. Images © T. E. Bunch, 2004

NWA 2106. Images © T. E. Bunch, 2004


Northwest Africa 2112

Northwest Africa
Found 2003
Achondrite (cumulate eucrite)

NWA 2112 Image © T. E. Bunch, 2004

A 67 g partial stone with fresh fusion crust was purchased in Erfoud, Morocco, April 2004. Description and classification (T. Bunch and J. Wittke, NAU): highly crushed monomict, granular to subophitic eucrite breccia; mm-sized (up to 2.4 mm) orthopyroxene and plagioclase both of which show prominent twinning; orthopyroxene also contains thin exsolution lamellae of Ca-rich pyroxene. Orthopyroxene, Fs46.5Wo2.8; augite, F26Wo34.2; plagioclase, An91, chromite, Cr[Cr+Al] = 0.81 and Mg/(Mg+Fe) = 0.23; metal, Ni = 0.56 wt%, and minor ilmenite. Shock level is S2-S4 with very thin melt veins that traverse the entire surface of a 5 cm long slice; limited maskelynite development. No apparent internal weathering. Specimens: type sample, 14.4 g NAU; main mass, Strufe.


Northwest Africa 2124

Northwest Africa
Purchased January 2004
Achondrite (polymict eucrite)

A 67 g complete stone, partially crusted, was purchased in Erfoud, Morocco. Description and classification (T. Bunch and J. Wittke, NAU): highly shocked (S3-5), medium-grained, polymict eucrite. Dominate lithology consists of orthopyroxene, Fs38.4Wo1.9 with exsolution lamellae of augite, Fs20.3Wo40.4, pigeonite, Fs34.4Wo13.7, plagioclase, An89.2, and chromite, Cr/[Cr+Al] = 62. The subordinate lithology contains orthopyroxene, Fs47.2Wo2.0; pigeonite, Fs43.2Wo14.7, plagioclase, An93.2 and chromite, Cr/[Cr+Al] = 0.701. Minor amounts of ilmenite and metal occur in both lithologies. Nearly 90 vol% of pyroxenes and plagioclase in both lithologies are shock-recrystallized; very light weathering grade. Specimens: 13.6 g, NAU; main mass, anonymous collector.

NWA 2124. Images © T. E. Bunch, 2004


Northwest Africa 2126

Northwest Africa
Purchased 2003
Achondrite (polymict eucrite)

NWA 2126. Image © T. E. Bunch, 2004

A complete and mostly crusted stone that weighted 227 g was purchased in Erfoud, Morocco. Description and classification (T. Bunch and J. Wittke, NAU): highly varied assortment of fine- to coarse-grained (0.2 to 3.4 mm) cumulate, ophitic, subophitic, microgranular to granular eucrites, howardite xenoliths, and shock melt clasts; numerous, discontinuous melt veins up to 1.6 mm in thickness. Coarse-grained cumulate pyroxenes range from Fs35.9Wo1.9 to Fs44.1Wo6.6; plagioclase, An90.6. Typical non-cumulate, low Ca pyroxenes, are Fs56.Wo5.8, Ca-rich pyroxenes, Fs32Wo35.3; plagioclase, An87. Melt veins have a limited compositional range and average (major oxides only): SiO2, 48.3 wt%; Al2O3, 15.7 wt%, FeO, 14.7 wt%, MgO, 6.2 wt% and CaO, 13.4 wt%. Shock level: S2-6; low degree of weathering. Specimens: 26.2 g, NAU; main mass, Hupé.

NWA 2126. Image widths = 13 mm. Images © T. E. Bunch, 2007


Northwest Africa 2128

Northwest Africa
Purchased 2004
Achondrite (polymict eucrite)

A small (40.1 g) partial stone was purchased in Erfoud, Morocco in January 2004. Description and classification (J. Wittke and T. Bunch, NAU): polymict eucrite that contains clasts (70 vol%) of very fine-grained (<0.01 mm) recrystallized pyroxene, plagioclase, and ilmenite together with sparse, relict megacrysts of pyroxene and plagioclase of similar compositions. Other clasts are partially recrystallized cumulate eucrites that are probably precursors of the recrystallized material. Recrystallized pyroxene, Fs61.2±1.2Wo5.7±1.1, FeO/MnO = 28.3; plagioclase, An91.1. Cumulate pyroxene, Fs56.3-62.4Wo2.3-8.9, FeO/MnO = 26.7-28.8; plagioclase, An92.1. Shock level, S5; very low grade weathering. Specimens: 8.2 g, NAU; main mass, Oakes.

NWA 2128. (left) plane-polarized light; (right) cross-polarized light; image width = 7 mm. Image © T. E. Bunch, 2007


Northwest Africa 2130

Northwest Africa
Purchased 2004
Achondrite (eucrite)

A single crusted stone of 506 g was purchased in Rissani, Morocco in January 2004. Description and classification (J. Wittke and T. Bunch, NAU): fine grained (<1 mm) subophitic eucrite basalt with numerous, cross cutting fractures (microns to hundreds of microns wide) that are filled with melt glasses. Orthopyroxene, Fs61.9Wo1.9, FeO/MnO = 26.6-30.8; pigeonite, Fs55.3Wo9; augite, Fs27.3Wo42; plagioclase, An88.3; Chromite, Cr/[Cr+Al] = 88.3. Also present are minor amounts of silica, metal and ilmenite. Shock level, S2-3 (melt glasses are injected); slightly weathered. Specimens: 21.7 g, NAU; main mass, Boswell.

NWA 2130. Images © T. E. Bunch, 2004

NWA 2130. Cross-polarized light; image width = 5 mm. Image © T. E. Bunch, 2007


Northwest Africa 2142

Northwest Africa
Purchased 2004
Achondrite (polymict eucrite)

NWA 2142. Image © T. E. Bunch, 2004

A single, complete and partially crusted stone was purchased in Rissani in January 2004. (T. Bunch and J. Wittke, NAU): contains an array of cumulate basaltic clasts of highly variable grain size (0.15 to 3.2 mm) and ~ 16 vol% of opaque, shock-melt xenoliths. The compositional range of major minerals in 9 cumulates (9 analyzed ) is rather small: orthopyroxene, Fs43Wo2.2 to Fs47.7Wo3.2; pigeonite, Fs40.4Wo13.8 to Fs46.6Wo14.2; plagioclase, An93.8- 94.5; chromite, Cr/[Cr+Al] = 0.68 to 0.74. Compositional similarities may suggest that many of these basalts may be related to a single volcanic event. Shock level, S2 and low weathering grade. Specimens: 21 g, NAU; main mass, Boswell.

NWA 2142. Images © T. E. Bunch, 2004


Northwest Africa 2199

Northwest Africa
Find: 2005
Achondrite (eucrite, monomict)

History and physical characteristics: A 156 g, complete stone was purchased from a dealer in Erfoud, Morocco in 2005 by Dr. David Gregory. The stone is moderately desert ablated with a remnant translucent fusion crust.
Petrography (T. Bunch and J. Wittke, NAU): monomict breccia with granoblastic matrix and partially recrystallized ophitic and subophitic basaltic pyroxenes. Unrecrystallized pyroxenes show partially annealed shock features (“decorations”) of fractures, planar deformation features, and shock twinning. Weathering effects are very low.
Mineral compositions: pyroxene host, Fs59Wo7 (FeO/MnO = 35); lamellae, Fs32.7Wo42.1. Plagioclase is An89.1. Also present is SiO2, ilmenite. metal, and merrillite.
Classification: Achondrite (eucrite, monomict breccia)
Type specimen: A total of 21 g are on deposit at NAU. Dr. David Gregory holds the main mass.

NWA 2199. Colorized BSE image showing recrystallized and recrystallized regions. Note exsolution in the pyroxenes (yellows and oranges). Plagioclase is purple-blue. Image © J. W. Wittke 2008.


Northwest Africa 2201

Northwest Africa
Find: 2005
Achondrite (eucrite monomict)

History and physical characteristics: A 27 g, complete stone was purchased from a dealer in Erfoud, Morocco in 2005 by Dr. David Gregory. The stone is highly polished by desert ablation with little remaining crust and is minimally chemically weathered.
Petrography (J. Wittke and T. Bunch, NAU): cumulate eucrite monomict breccia with intense comminution of subrounded clasts. The dark matrix is composed of very fine-grained mineral fragments and glassy filaments arranged together with clasts in a flow fabric. Some maskelynite and plagioclase glass are present. Weathering effects are minimal, with slight iron staining.
Mineral compositions: host pyroxene, Fs55Wo9.3 (FeO/MnO = 34-39); exsolution lamellae, Fs36.4Wo29; augite, Fs29.2Wo40.2. Plagioclase is An91 and chromite Cr/[Cr+Al] = 0.79. FeS, SiO2, and ilmenite are also present.
Classification: Achondrite (eucrite, monomict)
Type specimen:  A total of 5.5g are on deposit at NAU. Dr. David Gregory is the main mass holder.

NWA 2201. BSE image of clasts in flow fabric. Image © J. W. Wittke 2008.

NWA 2201. Colorized BSE image of clasts in flow fabric. Yellows = pryoxene; blue = plagioclase. Image © J. W. Wittke 2008.

NWA 2201. Colorized BSE image of merrillite rimed by CL-apatite. Image © J. W. Wittke 2008.


Northwest Africa 2356

Northwest Africa
Found 2004
Achondrite (polymict cumulate eucrite)

A 56 g complete stone was purchased in Erfoud, Morocco in March 2004. Description and classification (J. Wittke and T. Bunch, NAU): polymict, cumulate eucrite of mostly coarse-grained basaltic clasts (1 - 2.5 mm grain diameter). Most components are lightly to moderately shocked (S2-4) with a few shocked to S6. Low-Ca pyroxene, Fs37.1-43.1Wo2.8-3.7; pigeonite, Fs30.7-33.7Wo7.8-12.0; plagioclase, An88.9-92.1; chromite, Cr/[Cr+Al] = 0.77-0.85. Lightly weathered. Specimens: type specimen 22 g, NAU; main mass, Burkhard.

NWA 2356. Images © T. E. Bunch, 2007


Northwest Africa 2359

Northwest Africa
Found 2004
Achondrite (polymict cumulate eucrite)

A 1,298 g single stone with partial fusion crust was purchased in Erfoud, Morocco in March 2004. Description and classification (T. Bunch and J. Wittke, NAU): highly shocked, polymict eucrite breccia; up to 80 vol% of basalt clasts and mineral fragments were recrystallized into fine-grained masses (S5). In addition, earlier generated breccia clasts are present and are equally shocked; similar to NWA 2124. Average compositions are: low-Ca pyroxene, Fs54.6Wo3.2; pigeonite, Fs46.4Wo12.5; augite, Fs26.Wo40.8; plagioclase, An91.5; chromite, cr# = 87. Lightly weathered. Specimens: type specimen 21.1 g, NAU; main mass, Burkhard.


Northwest Africa 2362

Northwest Africa
Found 2003
Achondrite (cumulate eucrite)

A 252 g partially crusted stone was purchased in Erfoud, Morocco in May 2004. Description and classification (J. Wittke and T. Bunch, NAU): unbrecciated, medium-grained cumulate eucrite that is partially recrystallized. Orthopyroxene, Fs59.3-62.9Wo1.7-3.3 (FeO/MnO = 29.3-34.5), exsolved pigeonite, Fs55.1Wo9.1; augite; Fs22.4-26.3Wo43.1-44.8; plagioclase, An89.2; chromite, cr# = 80; low Ni metal (<0.25 wt% Ni), silica, and ilmenite. Shock level, S2 and low weathering grade. Specimens: 22.0 g, NAU; main mass, Birdsell.

NWA 2362. Note exsolved pyroxenes. Base width = 5 mm. © T. E. Bunch, 2007


Northwest Africa 2366

Northwest Africa
Found 2003
Achondrite (polymict eucrite)

Four stones with a total weight of 1239 grams were purchased in Erfoud, Morocco in May 2004. Description and classification (T. Bunch and J. Wittke, NAU): polymict breccia that contains a variety of basaltic textures including subophitic, phyric, cumulate (fine to coarse-grained varieties), variolitic, and shock melt. Phyric basalt: orthopyroxene phenocrysts, Fs56.4Wo3.0 (FeO/MnO = 34.5); groundmass augite, Fs35.6Wo34.2; plagioclase, An81.6. Coarse-grained cumulate: orthopyroxene, Fs43.9Wo1.9 (FeO/MnO = 37.3); exsolved pigeonite, Fs46.3Wo3.4; plagioclase, An94.9. Variolitic basalt: Fs59.0Wo2.9 (FeO/MnO = 35.3); subcalcic augite, Fs43.9Wo19.3; plagioclase, An76.5. Only very small amounts of ilmenite and no chromite were found in any rock type. All clasts and matrix are strongly shocked (S4-5, pyroxenes and plagioclase are mostly recrystallized); shock melt clasts are xenoliths, low weathering grade. Specimens: type specimen, 28 g, NAU; main mass, Birdsell.

NWA 2366. Base width = 13 mm. Image © T. E. Bunch, 2007


Northwest Africa 2650

Northwest Africa
Purchased 2004
Achondrite (cumulate eucrite)

A 2224 g complete stone that measures 189 mm x 112 mm x 82 mm at the widest points, with fresh crust was purchased in Erfoud, Morocco, Description and classification (T. Bunch and J. Wittke, NAU): cataclastic, cumulate eucrite; coarse-grained (plagioclase up to 7 mm and pyroxenes to 5 mm); zones of intense crushing with minor recrystallization; discontinuous melt veins and pockets. Plastic deformation and offset faulting in plagioclase; minor amounts of maskelynite; undulatory extinction, shock twinning, and reduced birefringence in pyroxenes; shock level, S3-5. Extensive development of albite, Carlsbad, and complex igneous twinning in plagioclase. Exsolution lamellae of subcalcic augite (Fs52.5Wo15.9) in inverted ferrohypersthene (Fs61.1Wo3.8) and separate grains of augite (Fs25.1Wo45.7), FeO/MnO of all pyroxenes between 32.2 and 34.8. Plagioclase, An90.8 and minor amounts of ilmenite and chromite, Cr/[Cr+Al] = 68-75. Low weathering grade. Specimens: type specimen, 23.1 g, NAU; main mass, D. Schultz.

NWA 2650. Base width = 6 mm. Image © T. E. Bunch, 2007


Northwest Africa 2659

Northwest Africa
Purchased 2004
Achondrite (eucrite)

A 509 g complete stone with light brown weathered crust was purchased in Tagounite. Morocco. Description and classification (T. Bunch and J. Wittke, NAU): highly shocked polymict, cumulate eucrite; fine- to medium-grained cumulate basalt clasts of irregular shapes and diffuse margins (shock level, S2-4) included within a mostly brecciated melt to recrystallized matrix (shock level, S3-6). Cumulate pyroxenes, Fs53.4Wo4.6 to Fs43.9Wo24.2; plagioclase, An90.1-94.6; chromite, Cr/[Cr+Al] = 64.3 -71.2; moderately weathered. Specimens: type sample, 23.1g, NAU; main mass, A. Hupe.


Northwest Africa 2724

Northwest Africa
Found 2004
Achondrite (polymict eucrite)

History: A 3804 g crusted complete stone was purchased in Erfoud, Morocco, in 2004.
Petrography: (J. Wittke and T. Bunch, NAU) The specimen mostly consists of cumulate basalt clasts that range from coarse-grained (~2 mm) to very fine-grained (~0.1 mm) with less than 5 vol% of subophitic basalts observed. Cumulate basaltic clasts are unusually low in ilmenite, chromite, and metal compared with other cumulate eucrites.
Composition: Despite the large range in grain size, pyroxene compositions show a rather narrow range: low-Ca pyroxenes (Fs59.1-62Wo3.2-3.8, pigeonite (Fs46.5-51Wo12.4-16.6, Ca-rich pyroxenes (Fs40-2.1Wo30.5-40., plagioclase (An89.4-92.
Classification: Achondrite (eucrite, polymict); low shock, minimal weathering.
Specimens: A 34 g type specimen is on deposit at NAU. E. Thompson holds the main mass.

NWA 2724. Base width = 15 mm. Images © T. E. Bunch, 2007


Northwest Africa 2751

Algeria
Find: 2004
Achondrite (polymict eucrite)

History and physical characteristics: A 43 g, partially crusted and lightly weathered stone was found in Algeria in 2004 and purchased in Rissani, Morocco in 2005.
Petrography: (T. Bunch and J. Wittke, NAU) polymict breccia that consists of a wide variety of basaltic clasts that include ophitic, subophitic, cumulate, and gabbroic with a limited shock level of S2-S3. Mineral compositions: Ophitic and subophitic orthopyroxenes, Fs47-61Wo2.1-3.0, FeO/MnO = 26-31, pigeonites, Fs44-54Wo0.3-12.0. Gabbro opx = Fs41Wo3.2. Plagioclase is An84-94. Chromite, Cr/[Cr+Al] = 0.78-0.88.
Classification: Polymict eucrite breccia.
Type specimen: A total of 9.2 g is on deposit at PSF. Mr. Matt Morgan holds the main mass.

NWA-2751. Cross-polarized light view. Note gabbroic clast in upper right corner. Base width = 9 mm. Image © T. E. Bunch, 2007.


Northwest Africa 2758

Northwest Africa
Purchased 2004
Achondrite (eucrite, polymict breccia)

History: Four partial stones weighing a total of 458 g were purchased in Erfoud, Morocco, in October 2004.
Petrography and Geochemistry: (J. Wittke and T. Bunch, NAU) The sample contains an assortment of cumulate (maximum grain size = 1.8 mm), subophitic (maximum grain size = 0.2 mm), and shock-melted to crystallized basalts. Cumulate basalts: Pyroxenes (Fs49.3Wo2.8; Fs38.8Wo13.9; Fs48.5Wo21.2; FeO/MnO for all = 31-40), plagioclase (An87); chromite (Cr/[Cr+Al] = 0.77). Subophitic basalts: Pyroxenes (Fs39.1-45.6Wo8.7-15.8; FeO/MnO = 30-36), plagioclase (An89) ,chromite (Cr/[Cr+Al] = 0.87).
Classification: Achondrite (eucrite, polymict breccia); low to high shock, minimal weathering.
Specimens: A 46 g type specimen is on deposit at NAU. Olsen holds the main mass.

NWA 2758. Base width = 10 mm. Images © T. E. Bunch, 2007


Northwest Africa 2784

Northwest Africa
Find: 2004
Achondrite (eucrite, polymict breccia)

History: A 141 g stone was purchased in Erfoud, Morocco, in October 2004.
Petrography: (T. Bunch and J. Wittke, NAU) A brecciated cumulate host (grain size up to 2.1 mm) with clasts of subophitic (maximum grain size, 0.12 mm) and recrystallized granular (average grain size, 0.03 mm) basalts.
Geochemistry: All analyzed lithologies are very similar in pyroxene and plagioclase composition. Orthopyroxenes (Fs62-64.1Wo2.1-2.8), Ca-rich pyroxene (Fs27-31.1Wo43.7-44.8), and plagioclase (An87.8-89.7). Pigeonite exsolution lamellae are too thin to analyze; cumulate contains Cr-rich ilmenite (Cr2O3 = 15.1 wt%) and Cr-poor ilmenite. Other lithologies contain chromite of similar composition, Cr/[Cr+Al] = 0.85, and minor ilmenite.
Classification: Achondrite (eucrite, polymict breccia); low shock (no maskelynite), minimal weathering.
Specimens: A 25 g type specimen is on deposit at NAU. Birdsell holds the main mass.

NWA 2784. Base widths = 9 mm. Images © T. E. Bunch, 2007


Northwest Africa 2824

NWA 2824. Base width = 13 mm. Image © T. E. Bunch, 2007


Northwest Africa 2913

Morocco
Purchased 2005
Achondrite (eucrite, monomict melt breccia)

History: A 100.2 g complete stone was purchased in Erfoud, Morocco, in May 2005.
Petrography: (J. Wittke and T. Bunch, NAU) Specimen contains medium-grained (<2 mm), centimeter-size, cumulate basalt clasts set in a microbreccia melt matrix. Clasts are moderately shocked with partial maskelynization of plagioclase and mechanical twinning, optical mosaicism and reduced birefringence in pyroxenes. The dark matrix is a flow mixture of FeO-rich glasses, very small cumulate basalt fragments, and patches of quench-textured microbasalt.
Geochemistry: Monomict cumulate basalt: host Ca-poor pyroxene (Fs55.4-57.8Wo5.1-2.9), FeO/MnO = 28; exsolved augite (Fs24.2Wo44.7), FeO/MnO = 36; plagioclase/maskelynite (An90.8); chromite Cr/[Cr+Al] = 0.86.
Classification: Achondrite (eucrite, monomict melt breccia); moderate shock, minimal weathering.
Specimens: A 21 g type specimen is deposited at NAU. Birdsell holds the main mass.

NWA 2784. Base widths = 9 mm. Images © T. E. Bunch, 2007


Northwest Africa 2914

Morocco
Purchased 2005
Achondrite (eucrite, monomict breccia)

History: Three paired partial stones weighing a total of 122 g were purchased in Erfoud, Morocco, in April 2005.
Petrography: (T. Bunch and J. Wittke, NAU) Cataclastic cumulate basalt that shows a remarkable range of shock features that include alternating bands of cataclastic and melt flows, mylonite-like swirls and lenticular masses, and rounded, finely crushed breccia clasts that are separated by dark, glassy to cryptocrystalline bands.
Geochemistry: Host: orthopyroxene (Fs59.3-62.7Wo3.1-1.9; FeO/MnO = 31), exsolved augite (Fs26.8-27.8Wo43-42.1; FeO/MnO = 28), plagioclase (An92); chromite (Cr/[Cr+Al] = 0.88).
Classification: Achondrite (eucrite monomict breccia) with moderate to high degree of shock and low degree of weathering.
Specimens: A 21.1 g type specimen is on deposit at NAU. Birdsell holds the main mass.

NWA 2914. Base width = 13 mm. Image © T. E. Bunch, 2007


Northwest Africa 2949

Morocco
Find: 2005
Achondrite (eucrite, polymict)

History and physical characteristics: A 1365 g stone was purchased from a dealer in Erfoud, Morocco in 2006. The stone has moderately fresh fusion crust that covers most of the surface.
Petrography (T. Bunch and J. Wittke, NAU): Contains medium to fine-grained cumulate, subophitic, and shock-melted clasts set in a fresh, light to dark gray matrix of cataclastic material. One medium-grained cumulate lithology has an unusual amount of tiny metal grains evenly distributed throughout the clasts.
Geochemistry: Medium-grained cumulate orthopyroxene = Fs41-50.9Wo2.0-4.8 (FeO/MnO = 30.5-34); pigeonite = Fs37.8Wo12.6; plagioclase, An90.3; chromite, Cr/(Al+Cr) = 0.88; and metal has 2.2 wt% Ni.
Classification: Achondrite (eucrite, polymict).
Type Specimen: A total of 29 g is on deposit at NAU. K. Davis holds the main mass.


Northwest Africa 2951

NWA 2951. Base width = 7 mm. Image © T. E. Bunch, 2007


Northwest Africa 2988

Algeria
Found 2006
Achondrite (eucrite)

History: The main-mass holders purchased the stone in Erfoud, Morocco in September 2006.
Physical characteristics: A single, complete stone of 4602 g with partial, moderately weathered fusion crust.
Petrography J. Wittke and T. Bunch, NAU): Microgranular (pyroxenes < 0.05 mm; plagioclase < 0.1 mm) with rare pyroxene splays and megacrysts of plagioclase and pyroxene (up to 0.6 mm in longest dimension), At least two brecciation episodes (breccia-in-breccia) are crosscut by shock melt injection veins. These melt veins have bulk major- and minor-element compositions consistent with typical eucrite bulk compositions. The stone contains orthopyroxene, augite, plagioclase, chromite, and troilite.
Geochemistry: Orthopyroxene, Fs61Wo2.1; augite, Fs42.3Wo37.8; chromite, Cr/[Cr+Al] = 0.81; plagioclase, An92.3. EMP broad beam analysis of the shock melt glass is: Si = 22.75; Al = 8.7; Ca = 9.45, Ti = 0.45; Cr = 0.21; Fe = 12.4; Mg = 3.1; Mn = 0.3 (all wt%).
Classification: Achondrite (eucrite); S5; minimal weathering.
Type specimens: A total of 20.1 g and one thin section are on deposit at NAU. Farmer and Strope hold the main mass.

NWA 2988. A 10 x 10 cm slice of breccia-in-breccia and thin, dark melt injection veins. Image © T. E. Bunch, 2004


Northwest Africa 3122

Northwest Africa
Found 2003
Achondrite (eucrite, polymict)

NWA-3122. Image © T. E. Bunch, 2004

A 131 g stone was purchased in Morocco in Morocco, September 2003. Description and classification (T. Bunch and J. Wittke, NAU): dark to medium gray, brecciated eucrite that essentially contains medium to fine-grained cumulate eucrites. Highly shocked (S4-5): maskelynite and solid state recrystallization of plagioclase; reduced birefringence and recrystallization of pyroxenes; localized melt pockets. Dominate basalt lithology: low-Ca pyroxenes, Fs56.1-59.3Wo1.4-1.8 (Fe/Mn = 32-34.8), exsolution lamellae (Fs35.Wo28.8); augite, Fs23.5Wo43.1. Plagioclase is unusually sodic and slightly zoned, An68-70Or8.2-2.0; chromite, Cr/[Cr+Al] = 81 and Fe/(Fe+Mg) = 98.7; low Ni metal (0.32 wt% Ni and 0.52 wt% Co). Lightly weathered. Specimens: 21.1 g, NAU; main mass, Hupé.

NWA 3122 © T. E. Bunch, 2004


Northwest Africa 3129

Northwest Africa
2003
Achondrite (eucrite)

NWA 3129. Image © T. E. Bunch, 2004

A single, partially crusted 132.1 g stone was purchased in Erfoud in February 2004. Description and classification (T. Bunch and J. Wittke, NAU): light to medium gray, microcrystalline (< 0.3 mm, mean grain size of ~0.2 mm), subophitic basalt; fractured with interclast granulation and recrystallization; minor clast rotation. Pigeonite, Fs56.3-63.5Wo16.1-6.5with submicron exsolution lamellae; Ca-pyroxene, Fs49Wo27.9; plagioclase, An90.8, chromite, Cr/[Cr+Al] = 92.7, troilite, ilmenite, metal, and silica. Shock level, S2-3; low grade weathering. Specimens: 20.1, NAU; main mass, Oakes.


Northwest Africa 4287

Algeria
Find: 2005
Achondrite (eucrite monomict breccia)

History: A 364 g stone was found in Southern Algeria and purchased in Erfoud, Morocco, in November 2005.
Physical characteristics: Primary and secondary ablation crust partially cover the stone.
Petrography (J. Wittke and T. Bunch, NAU): monomict breccia with subrounded, cm-sized clasts of subophitic basalt set in a cataclastic matrix. Thin bladed plagioclase up to 5 mm in length encloses granular anhedral pyroxenes, chromite, and ilmenite. Sparse areas of ophitic-textured basalt also occur.
Geochemistry: Orthopyroxene host is Fs59-63.7Wo3.3-4.1, augite exsolution lamellae are Fs26.1-28.9Wo44.2, plagioclase is An87 and chromite Cr/[Cr+Al] = 0.83-0.88.
Classification: Achondrite (eucrite monomict breccia). Shock level is S2 and the weathering grade is very low.
Type specimens: A total of 30 g and one thin section are on deposit at NAU. Thompson holds the main mass.

NWA 4287. Base width = 13 mm. Image © T. E. Bunch, 2007


Northwest Africa 4496

Northwest Africa
Find 2006
Achondrite (cumulate eucrite)

History: A stone was found by an individual while tending to a goatherd and purchased in Rissani in July 2006.
Physical characteristics: A complete and elongated 19 g stone with fresh fusion crust.
Petrography (J. Wittke and T. Bunch, NAU): Fine- to medium-grain-size, monomict cumulate eucrite with plastic flow features. Clusters of interpenetrating plagioclase crystals that display prominent albite twinning, enclose pyroxenes.
Geochemistry; Orthopyroxene, Fs59.7-61Wo3.8; FeO/MnO = 31-33, n = 15); pigeonite, Fs52.1-55Wo6.9-11.2; ferroaugite, Fs47.8Wo27.2; plagioclase, An89-92, chromite, Cr/[Cr+Al] = 0.69.
Classification: Achondrite, (eucrite, cumulate, monomict breccia); minimal shock and weathering.
Type specimens: A total of 4.1 g and one thin section are on deposit at NAU. The main mass holder is anonymous.


Northwest Africa 4541

Algeria
Find: 2006
Achondrite (basaltic eucrite, monomict breccia)

History and physical characteristics: Found in Algeria and purchased from a dealer in Erfoud, Morocco by S. Turecki in 2006. The single 168 g stone has a fresh, black fusion crust.
Petrography: (J. Wittke and T. Bunch, NAU) Fine-grained (< 0.35 mm), subophitic basalt breccia, dominated by sub-rounded clasts that are set in a cataclastic matrix. Minimal weathering and low to moderate shock level.
Mineral compositions: Pigeonite (Fe54.7-59.4Wo4.4-7.3; FeO/MnO = 31-34), augite (Fs38Wo46.5), plagioclase (An94.3), chromite (Cr/[Cr+Al] = 0.85), with minor ilmenite and silica.
Classification: Achondrite (basaltic eucritic, monomict breccia)
Type specimen: A 20 g sample is on deposit at NAU. Mr. S. Turecki is the main mass holder.

NWA 4541. Base width = 7 mm. Image © T. E. Bunch, 2007


Northwest Africa 4596

NWA 4596. Base width = 13 mm. Image © T. E. Bunch, 2007


Northwest Africa 4824

Northwest Africa
Find: 2007
Achondrite (eucrite, monomict breccia)

History and physical characteristics: A 97 g fully crusted, fresh stone was purchased in Tucson at the Tucson Gem and Mineral Show in January 2007.
Petrography (J. Wittke and T. Bunch, NAU): Highly shocked monomict, basaltic eucrite breccia. Partially recrystallized with maskelynite and plagioclase glass, mosaic to recrystallized pyroxenes, and dark, shock-melt clasts.
Mineral compositions: Pigeonite host, Fs56.6Wo5.7; augite lamellae, Fs33.2Wo32.6. Plagioclase is An90.8.
Classification: Achondrite (eucrite, monomict breccia).
Type specimen: 19.7 g are on deposit at NAU. The main mass holder is anonymous.


Northwest Africa 4825

Northwest Africa
Find: 2006
Achondrite (eucrite, polymict)

History and physical characteristics: A 226 g complete stone with moderately fresh fusion crust was purchased in Tucson at the Tucson Gem and Mineral Show in January 2007.
Petrograpy (J. Wittke and T. Bunch, NAU): A brecciated polymict eucrite with cataclastic flow veins and partially recrystallized matrix. Consists of cumulate, subophitic, and ophitic basalt clasts. A portion of the plagioclase was converted to maskelynite by shock and most pyroxenes are shock-decorated. Shock level is S4 and the weathering grade is very low.
Mineral compositions: subophitic orthopyroxene host, Fs56.8Wo3.6 (FeO/MnO = 30-32); exsolution lamellae, Fs29Wo39.5. Pigeonite is Fs56.7Wo8.8 and plagioclase is An90.2-94.5. Minor minerals include silica, chromite, ilmenite, and FeS.
Classification: Achondrite (eucrite, polymict).
Type specimen: A total of 23.1 g is on deposit at NAU. The main mass holder is anonymous.


Northwest Africa 4830

Northwest Africa
Find: 2006
Achondrite (eucrite, monomict)

History and physical characteristics: A 38 g fully crusted stone with moderately fresh fusion crust was purchased at the Denver Gem and Mineral in September 2006.
Petrography (T. Bunch and J. Wittke, NAU): This stone is a monomict, eucrite basalt with granoblastic texture. Most of the sample was recrystallized into an assemblage of very fine-grained polygons (< 0.03 mm). Vestiges of the original texture show a fabric of divergent plagioclase laths and interstitial pyroxenes. Maximum length of the plagioclase laths is < 0.4 mm. Early shock effects were probably annealed out during recrystallization. The last shock episode is S2 and weathering effects are minimal.
Mineral compositions: (relict and recrystallized minerals are essentially the same). Orthopyroxene, Fs60.5Wo2.1 (FeO/MnO = 32); augite, Fs37.4Wo35.5; plagioclase, An93; chromite Cr/[Cr+Al] = 0.84.
Classification: Achondrite (eucrite. monomict).
Type specimen: A total of 7.7 g is on deposit at NAU. The main mass holder is anonymous.


Northwest Africa 4831

Northwest Africa
Find: 2006
Achondrite (eucrite, monomict cumulate)

History and physical characteristics: A 154 g, partial stone with moderately fresh fusion crust, was purchased at the Denver Gem and Mineral Show in September 2006.
Petrography (J. Wittke and T. Bunch, NAU): A monomict cumulate eucrite with breccia-within-breccia texture. Clasts tend to be subrounded and contain orthopyroxenes that are commonly devoid of exsolved Ca-pyroxenes. Plagioclase contains micros-sized oriented pyroxene inclusions. Shock level is S3-S4 and the weathering grade is low.
Mineral compositions: Orthopyroxene, Fs46.7-52Wo2.2-3.1 (FeO/MnO =32); augite, Fs36.4Wo44.7; plagioclase An88-91.1.
Classification: Achondrite (eucrite, monomict cumulate).
Type specimen: A total of 21.4 g is on deposit at NAU. The main mass holder is anonymous.


Northwest Africa 4834

Algeria
Find: 2006
Achondrite (eucrite, polymict)

History and physical characteristics: A very fresh, partial 50 g stone with bubbly fusion crust was purchased in Erfoud, Morocco in 2007. Large areas crushed to white, powdery rock flour.
Petrography (J. Wittke and T. Bunch, NAU): Fine-grained (few clasts exceed two mm) polymict breccia of cumulate, ophitic, subophitic basalts and shock-melt clasts set in a cataclastic matrix. No oxidation of rare metal grains, equivalent to W0/1. Shock level of clasts ranges from S2 to S6.
Geochemistry: Ophitic basalt: orthopyroxene host, Fs57.4Wo3.2 (FeO/MnO = 32; exsolution lamellae, Fs32.6Wo34.8; Plagioclase, An92.7; chromite, Cr/(Al+Cr) = 0.86.
Classification: Achondrite (eucrite, polymict).
Type sample: A total of 10 g are on deposit at NAU. Cimala holds the main mass.

NWA 4834. Base width = 13 mm. Image © T. E. Bunch, 2010


Northwest Africa 4960

Northwest Africa
Find: 2007
Achondrite (eucrite, monomict breccia)

History and physical characteristics: A single 29 g stone was purchased in Erfoud Morocco in August 2007. Some fusion crust remains, although much has been wind ablated away leaving a translucent surface, chemical weathering is minor.
Petrography (T. Bunch and J. Wittke, NAU): Monomict cumulate basalt breccia that is highly shocked. Plagioclase is completely recrytallized. Pyroxenes are partially recrystallized, unrecrystallized pyroxenes have reduced birefringence, shock lamellae, and are darkened by shock decorations. Unusual amount of metal for a eucrite (vol% = 4). Sparse, but large chromite grains (0.3 to 1.1 mm) are present. Weathering grade is low with some staining around metal grains.
Mineral compositions: Fs45.7Wo1.9 (FeO/MnO = 28); lamellae, Fs8.2Wo14.8; augite, Fs16.6Wo46.1. Plagioclase, An87.8, chromite Cr/[Cr+Al] = 0.81, and metal Ni = 0.87 wt%.
Classification: Achondrite (eucrite, monomict breccia).
Type specimen: A total of 5.9 g is on deposit at NAU. Mr. M. Cimala holds the main mass.


Northwest Africa 4963

Northwest Africa
Find: 2007
Achondrite (eucrite, monomict breccia)

History and physical characteristics: A single 188 g single stone was purchased in Erfoud, Morocco in August 2007. The fusion crust is very fresh with only minor desert ablation and staining.
Petrography (J. Wittke and T. Bunch, NAU): Monomict eucrite breccia that consists of subophitic decorated basalt clasts set in a crushed matrix. The interior is very fresh and the shock level is moderate.
Mineral composition: Orthopyroxene host pyroxene is Fs62Wo8.3, lamellae are Fs55.8Wo8.3, augite is Fs28.4Wo42. Plagioclase is An88.8 and chromite Cr/[Cr+Al] = 0.83.
Classification: Achondrite (eucrite, monomict breccia).
Type specimen: A total of 20 g is on deposit at NAU. The main mass holder is Mr. M. Cimala.

NWA 4963. Base width = 13 mm. Image © T. E. Bunch, 2010


Northwest Africa 4968

Algeria
Find: 2007
Achondrite (eucrite, polymict)

History and physical characteristics: A 366 g stone was purchased in Erfoud, Morocco by M. Cimala in 2007. The stone is partially covered by wind-ablated fusion crust.
Petrography (J. Wittke and T. Bunch, NAU): Polymict breccia that consists of fine to medium grained ophitic to subophitic basalts. Weathering grade is low, slight staining of metal grains. Shock level is low to medium in the various basaltic clasts.
Geochemistry: Medium grained clasts: host orthopyroxene, Fs59.3Wo4.3 (FeO/MnO = 30); exsolution lamellae, Fs30.9Wo38.4; pigeonite, Fs48.5Wo8.7; plagioclase, An91.7; chromite, Cr/(Al+Cr) = 0.84.
Classification: Achondrite (eucrite, polymict).
Type specimen: A total of 20.4 g are on deposit at NAU. Cimala holds the main mass.

NWA 4968. Base width = 13 mm. Image © T. E. Bunch, 2010


Northwest Africa 5218

Northwest Africa
Find: 2007
Achondrite (eucrite, shock melt breccia)

History and Physical Characteristics: A very dark 76 g stone with little fusion crust was found in Algeria and purchased in Erfoud in October 2007.
Petrography (T. Bunch and J Wittke, NAU): Large, partially melted cumulate basalt clasts are set in a shock melt flow that consists of partially melted basalt fragments and quenched, subophitic microbasalt. The large clasts and fragments are subrounded and show margin resorption. The overall shock level is medium to high (S3-5).
Mineral compositions: Cumulate orthopyroxene is Fs54.3-60Wo3.3-4.9; exsolved augite is Fs25.9Wo45. Plagioclase is An92.9.
Classification: Achondrite (eucrite, shock melt breccia).
Type specimen: A total of 15.4 g is on deposit at NAU. Cimala is the main mass holder.

NWA 5218. Base width = 23 mm. Image © T. E. Bunch, 2007


Miscellaneous Eucrites

IDLocationDateMass (g)StateFaFsComments
NWA 2655Erfoud, Morocco2004257S4-5-57 & 34.8 paired with NWA 2366