CK Carbonaceous Chondrites


Dhofar 1430 (18°34'10"N 54°14'24"E)

Oman
Find: March 06, 2006
Carbonaceous chondrite (CK3)

History and physical characteristics: A 185 g complete, poorly crusted stone was found in the Dhofar region by M. Farmer and R. Ward March 06, 2006.
Petrography: (J. Wittke and T. Bunch, NAU) Greenish gray stone that has a poorly crystallized matrix of olivine, augite, plagioclase, feldspathic glasses, orthopyroxene, Cr-magnetite, ilmenite, pyrite, pyrrhotite, and pentlandite. Contains many heavily mantled chondrules (up to 1.4 mm in dia.), compound chondrules, relict dusty olivine grains within porphyritic chondrules, single crystals of zoned olivine (0.3-0.85 mm in dia.) and poorly crystallized, plagioclase-rich objects.
Mineral compositions and geochemistry: Matrix olivine (Fa29.3-34.5, NiO = 0.78 wt %, FeO/MnO = 95-133 g/g); orthopyroxene (Fs23.3Wo2.3); augite (Fs12Wo24.3); plagioclase/feldspathic glasses (An38-78) and Cr-magnetite (Cr2O3 = up to 6.6 wt %).
Classification: CK3 carbonaceous chondrite., light to moderately weathered and lightly shocked (S2).
Type specimens: A sample of 20.1 g is on deposit at NAU. Robert Ward is the main mass holder.


Northwest Africa 772 (26°26.96' N, 11°41.61' W)

Morocco
Found October 2000
Carbonaceous chondrite (CK3)

A 71 g crusted stone was found southwest of Raudat Haua by a person prospecting for meteorites. Mineralogy and classification (T. Bunch and J. Wittke, NAU): modes (vol. %) are matrix = 58, chondrules = 32, sulfides = 7, Cr-magnetite = 2, refractory inclusions = 1; chondrule sizes range from 50 µm to >1 mm; chondrule type modes (vol. %) are porphyritic olivine = 21, porphyritic olivine-pyroxene = 4, cryptocrystalline = 3, granular olivine = 3, other = 1; matrix is mostly uncrystallized; fine grained olivine, Fa35, NiO = 0.25 wt. %; plagioclase, An80; Ca-rich pyroxene Wo46Fs9; Ca-poor pyroxene Fs19.6; contains Ni-rich sulfides and Cr-rich magnetite (Cr2O3 = up to 13.9 wt. %); weathering grade, W0/1. Specimens: 13.8 g plus thin section, NAU; main mass with finder.

NWA 772. Image © T. E. Bunch, 2004


Northwest Africa 1112

Morocco
2001
Carbonaceous chondrite (CK5)

A 49 g complete stone was purchased in Erfoud, Morocco October 2001. Classification and mineralogy (T. Bunch and J. Wittke, NAU): well equilibrated, abundant matrix (~75 vol. %). Matrix olivine, Fa30.1 (range Fa29.9-30.3); (O.46 wt. % NiO); plagioclase, An31.8Or4.1 (range An28.3-38); green diopside, Fs1.5Wo45.2En45.2. Magnetite Cr2O3 and Al2O3 contents are lower in abundance than in less equilibrated CKs, 3.87 wt. % and 0.29 wt. %, respectively, with TiO2, 0.27 %; MnO 0.18 %; NiO, 0.31 % and CoO, 0.14 %. Phosphate and Ni-, Co-rich pyrrhotite. Very fresh. Shock level, S2. Specimens: type specimen, 9.1 g, NAU; main mass, Hupé.


Northwest Africa 1284

Morocco
2001
Carbonaceous chondrite (CK4/5)

A 56 g stone was purchased in Erfoud in October 2001. Classification and mineralogy (J. Wittke and T. Bunch, NAU): mostly recrystallized olivine-rich matrix with poorly crystallized plagioclase (mottled extinction, low birefringence, and up to 0.12 wt. % NiO). Matrix olivine, Fa31.5 (range, Fa31.1-32.0) (0.45 wt. % NiO); plagioclase, An51.8Or5 (range An44.5-63.1); magnetite, 4.6 wt. % Cr2O3; 1.62 % Al2O3; 0.31 % NiO; 0.37 % TiO2; 0.25 % CoO and 0.17 % MnO. Contains minor pentlandite, pyrrhotite, and phosphate. Low degree of weathering and shock level, S2. Specimens: 11.3 g, NAU; main mass, Hupe.


Northwest Africa 1628

Northwest Africa
Found 2003
Carbonaceous chondrite (CK5)

A 35.7 g stone was purchased in Rissani, Morocco in September 2003. Description and classification (T. Bunch and J. Wittke, NAU): Partially shock-melted/crystallized CK (S3-6) of undeterminable petrologic grade. Cataclastic matrix consists of massive olivine (Fa31) with many microns-size magnetite inclusions (Cr2O3 = 0.57 wt. %; Al2O3 = 3.1 wt. %) and plagioclase (An29.3). Several chondrules with thick, fine-grained rims, are mantled with felty masses of quench-form, alumina-rich, low-Ca pyroxene (Fs23.2En76.8), set in Ca-rich mesostasis. Many other chondrules also show characteristics of partial melting. Medium weathering grade. Specimens: 7.8 g, NAU; main mass, Oakes.


Northwest Africa 1694

Morocco
Found 2002
Carbonaceous chondrite (CK3)

NWA 1694. Image © T. E. Bunch, 2004

A 47.1 g stone was purchases in Safsaf, October 2002. Mineralogy and classification (T. Bunch and J. Wittke, NAU): fresh stone (shiny fusion crust with slight interior staining near the surface) with 80 % fusion crust. Modes (in vol. %): matrix, 47; chondrules, 44; sulfides, 6; Cr-magnetite, 2; refractory inclusions, 1. Chondrules range in size from 0.08 to 1.2 mm. Matrix mostly unrecrystallized, fine-grained (<5 µm) olivine, Fa37; augite, Fs15Wo47; Ca-poor pyroxene, Fs29; Ni-rich sulfides (Co up to 0.84 wt. %) and Cr-rich magnetite (Cr2O3 up to 16.51 wt. %). Sulfides contain many small (<20 µm), rounded inclusions of Cl-apatite and SiO2 glass. Similar to, but not paired with NWA 772. Contains Ca,Al-rich inclusions. Shock level, S1; weathering grade, W0/1. Specimens: type specimen, 9.42 g and one thin section, NAU; main mass, Hupé.


Northwest Africa 1907

Morocco
Found 2003
Carbonaceous chondrite (CK5)

NWA 1907. © T. E. Bunch, 2004

A 476 g stone was purchased in Rissani in June 2003. Classification and mineralogy (J. Wittke and T. Bunch, NAU): coarse, recrystallized matrix and some chondrule margins. Olivine is equilibrated at Fa32.2 (range 32.1-32.4) with NiO = 0.52 wt. %; large patches of plagioclase with variable composition between An32 and An60; magnetite contains 5.3 wt. % Cr2O3 and 1.88 wt. % Al2O3; troilite, and phosphate. Shock level, S2/3; weathering grade, W2. Specimens: type specimen, 22.15 g, NAU; main mass, Farmer.


Northwest Africa 2129

Northwest Africa
Found 2003
Carbonaceous chondrite (CK3/4)

A 994 complete, mostly crusted stone was purchased in Erfoud in December 2003. Description and classification (T. Bunch and J. Wittke, NAU): well-defined chondrules in a partially crystallized matrix. Matrix olivine, Fa30.3-33.9, NiO = 0.54 wt. %; magnetite, Cr2O3 = 6.0-7.2 wt. %, Al2O3 = 1.92 wt. %, NiO = 0.41 wt. %, TiO2 = 0.5 wt. %. Transitional assignment of CK3/4 made on the basis of heterogeneous matrix, olivine composition, and magnetite composition (> 9 wt. % Cr2O3 in CK3s and < 6 wt. % in CK4s). Shock level, S2 and low weathering grade. Specimens: 23.4 g, NAU; Main mass, Hupé.


Northwest Africa 2372

Northwest Africa
Found 2004
Carbonaceous chondrite (CK4)

A 440 g single, brownish stone was purchased in Erfoud, Morocco in May 2004. Description and classification (T. Bunch and J. Wittke, NAU): contains ~33 vol. % chondrules that are typically smaller than most CK meteorites (<1 mm diameter), abundant melilite-spinel CAIs rimmed by subcalcic augite, and partially rcrystallized matrix. Matrix olivine, Fa29.5-34.2 (FeO/MnO = 30.8-37.8 g/g); low-Ca pyroxene, Fs25.3-29.0Wo0.9-5.3 (FeO/MnO = 25.3-29.0 g/g); plagioclase, An36.8-51.2Or1.7-3.0; magnetite, Cr2O3 = 5.3 wt. %, Al2O3 = 5.3 wt. %, TiO2 = 1.97 wt. %, troilite, and Fe-, Mg-rich feldspathic glass. A portion of the glass has been replaced by terrestrial carbonate. Shock level is S2, weathering grade, W3. Specimens: type specimen, 23 g, NAU; main mass. Reed.


Northwest Africa 2386

Northwest Africa
Purchased September 2004
Carbonaceous chondrite (CK4)

A 440 g single stone with weathered crust was purchased in Erfoud, Morocco. Description and classification (J. Wittke and T. Bunch, NAU): contains ~42 vol. % small chondrules with ~13 vol. % CAI components dominated by melilite-spinel aggregates, rimmed by diopside or subcalcic augite. Chondrules have well-defined rims and mostly crystallized mesostasis. Matrix is partially recrystallized with minor Fe-, Mg-rich feldspathic glasses. Olivine is fine-grained and poorly crystallized. Matrix olivine, Fa29.5-34.8 (FeO/MnO = 31-37 g/g); low-Ca pyroxene, Fs25.3-29.0Wo0.9-5.3 (FeO/MnO = 25.3-29.0 g/g); plagioclase, An41.0-51.2Or2.1-2.9; magnetite, Cr2O3 = 5.3 wt. %, Al2O3 = 1.86 wt. %, TiO2 = 1.97 wt. % and NiO = 0.31 wt. %. Moderately weathered and lightly shocked (S2). Specimens: type specimen, 22 g, NAU; main mass, Reed.


Northwest Africa 2388

Northwest Africa
Purchased 2004 September
Carbonaceous chondrite (CK6)

An 81 g fresh and fully crusted stone (with primary and secondary ablation surfaces) was purchased in Erfoud, Morocco. Description and classification (T. Bunch and J. Wittke, NAU): fully equilibrated and recrystallized with a few indistinct, relict chondrules. Abundant plagioclase forms a discontinuous network around enclaves of olivine, Ca-pyroxene, and magnetite matrix and around relict chondrules. Olivine in matrix and chondrules is very homogeneous, Fa 31.9-32.6 (N = 26) and very low MnO contents (FeO/MnO = 113-137 g/g); Ca-pyroxene, Fs20.5Wo50.5 (FeO/MnO = 98-118 g/g); plagioclase, An85.9Or7.4. All silicates contain NiO: olivine, 0.62-0.82 wt. %, Ca-pyroxene, 0.78-1.09 wt. %, plagioclase, 0.41-0.49 wt. %. Magnetite, Cr2O3 = 5.3 wt. %, Al2O3 = 2.36 wt. %, NiO = 0.51 wt. %. Moderately weathered and low shock level. Specimens: type specimen, 16.2 g, NAU; main mass, Reed.


Northwest Africa 2708

Morocco
Found 2004
Carbonaceous chondrite (CK4)

History: A single partially crusted stone of 528 g was purchased in Erfoud, Morocco, in January 2005.
Petrography: (J. Wittke and T. Bunch, NAU) Specimen contains rare, partially altered CAI; melt clasts and chondrules with fairly sharp margin/matrix boundaries. Geochemistry: Matrix olivine (Fa29.7±2.7), magnetite (Cr2O3 = 4.6, Al2O3 = 2.19 [both wt. %]), poorly crystallized plagioclase (An78.4, pentlandite (Co = 1.87 wt%). Chondrules: Olivine (Fa30.6±1.95), Ca-rich pyroxene (Fs43.5Wo48.7), magnetite (Cr2O3 = 3.2, Al2O3 = 1.0 [both wt. %]). Magnetite in melt clasts contains Ni-bearing, exsolved ilmenite.
Classification: Carbonaceous chondrite (CK4); host = low shock; clasts = moderate to highly shocked, moderate weathering.
Specimens: A 20.3 g type specimen is on deposit at NAU. G. Hupé holds the main mass.


Northwest Africa 3116

Morocco
Found 2002
Carbonaceous chondrite (CK5)

A 27 g stone was purchased in Erfoud, Morocco in 2002. Description and classification (T. Bunch and J. Wittke, NAU): contains numerous amoeboid and melilite-spinel - rich CAIs; well crystallized matrix of mostly fine-grained olivine (Fa35.4), plagioclase (An39.5), magnetite (Cr2O3 = 2.93 wt. %; Al2O3 = 2.85 wt. %; MgO = 0.65 wt. %; P2O5 = 0.35 wt. %; TiO2 = 0.85 wt. %; NiO = 0.43 wt. %; CoO = 0.26 wt. %), and troilite. Several large xenoliths of shock-melted/crystallized material contains sheaths of Ca-rich pyroxene (Fs14.1Wo49.1) set in a groundmass of microns-size Ca-poor pyroxenes (Fs34.2Wo2.0) and pentlandite (Ni = 36.7 wt. %). Shock level, S3 (xenoliths, S6); low weathering grade. Specimens: 5.4 g, NAU; main mass, Hupé.

NWA 3116. © T. E. Bunch, 2004


Northwest Africa 4657

Northwest Africa
Find: 2006
Carbonaceous chondrite (CK4)

History and physical characteristics: Purchased by B. Reed from a dealer in Erfoud, Morocco in 2006. The single stone is a light greenish-gray, 417 g stone that is partially crusted on ~ 70 % of the surface and moderately to heavily desert-etched on the remaining surface.
Petrography: (J. Wittke and T. Bunch, NAU) Contains ~ 18 vol. % well-defined chondrules, some of which are up to 2 mm in diameter. The matrix is partially recrystallized with tiny plagioclase grains intermingled with amorphous plagioclase aggregates. Chondrule glass is mostly devitrified.
Mineral compositions and geochemistry: Olivine shows a narrow molecular FeO spread, although at lower values (Fa27.3-28.2) compared with typical CK chondrites; FeO/MnO = 95-123 g/g. Orthopyroxene (Fs23.8Wo2.2), magnetite (Cr2O3 = 3.79 wt. %; Al2O3 = 1.56 wt. %; NiO = 0.90 wt. %), plagioclase (An27.9-49).
Classification: Carbonaceous chondrite (CK4), moderate weathering and low shock.
Type specimen: A 23 g sample is on deposit at NAU. B. Reed holds the main mass.


Northwest Africa 4661

Algeria
Find: 2005
Carbonaceous chondrite (CK3)

History and physical characteristics:  A 42 g dark stone with partial fusion crust and deep, desert ablation etching was found in Algeria in 2005 and purchased in Rissani in 2006 by H. Burkhard.
Petrography: (J. Wittke and T. Bunch, NAU) Fresh light gray interior with unusually large chondrules (up to 3 mm, mean = 0.95 mm) for a CK chondrite. Chondrules have sharply defined boundaries and contain clear glass. Inclusions of apatite occur in matrix magnetite. Isotropic clumps of near plagioclase compositions are heterogeneously dispersed within the matrix.
Mineral compositions and geochemistry: Olivine (Fa21.5-37.4; FeO/MnO = 90-177 g/g), Ca-pyroxene (Fs9.1-14.2Wo45-49.7), isotropic “plagioclase” (An27.8-73.2); magnetite (Cr2O3 = 1.79-2.25 wt. %; Al2O3 = 1.22-2.28 wt. %; MgO = 0.25-0.42 wt. %; NiO = 0.25-0.45 wt. %.
Classification: Carbonaceous chondrite (CK3); low weathering grade and low shock level.
Type specimen: An 8.3 g sample is on deposit at NAU. H. Burkhard owns the main mass.


Northwest Africa 4812

Northwest Africa
Find: 2006
Carbonaceous chondrite (CK)

History and physical characteristics: A 68 g stone was purchased in Erfoud, Morocco by Stefan Ralew in 2006. Patchy distribution of dark gray fusion crust and desert etching.
Petrography (T. Bunch and J. Wittke, NAU): dark interior with very dark chondrules and shock-melt clasts, the matrix is nearly opaque. Highly shocked and shock-darkened by melting to partial melting of matrix and redistribution of fine-grained magnetite similar to shock darkening of ordinary chondrites and redistribution of fine-grained metal droplets. Contains olivine, orthopyroxene, pigeonite, plagioclase, felsic glasses, Cr-magnetite, FeS, and pentlandite. The shock level is very high at S5 and the weathering grade is low.
Mineral compositions: Olivine, Fa30.3 (FeO/MnO = 110); orthopyroxene, Fs26.4Wo0.7 (FeO/MnO = 74); pigeonite, Fs21.1Wo12.1 (FeO/MnO = 64); plagioclase, An59.3 and magnetite, Cr2O3 = 3.64 wt. % and Al2O3 = 1.26 wt. %.
Classification: Carbonaceous chondrite (CK). High shock effects preclude further subtype classification.
Type specimen: A total of 3.9 g and one thin section are on deposit at NAU. Mr. Stefan Ralew is the main mass holder.


Northwest Africa 4964

Algeria
Find: 2007
Carbonaceous chondrite (CK3)

History and physical characteristics: A single 456 g stone was purchased in Erfoud in October 2007. The stone lacks fusion crust and is highly polished and etched from wind ablation, several chondrules stand out on top of the surface. The surface chemical weathering grade is low.
Petrography (T. Bunch and J. Wittke, NAU): Gray to buff-colored with abundant CAIs and thickly mantled chondrules. Orthopyroxenes are polysynthetically twinned in several chondrules, olivine is commonly zoned. Matrix is mostly a mass of porous olivine with patches of zoned plagioclase that are surrounded by felty masses of fine-grained glasses. Orthopyroxene, Ca-pyroxene, Cr-magnetite, FeS, pentlandite, pyrrhotite, and ilmenite are also present.
Classification: Carbonaceous chondrite (CK3).
Type specimen: A total of ??? g is on deposit at NAU. Cimala holds the main mass..


Photographs of CK Chondrites

NWA 2787. © T. E. Bunch, 2005


Other CK Carbonaceous Chondrites

IDLocationDateMass (g)StateFaFsComments
NWA 2688 Erfoud, Morocco2004123S3, W227.5- An60; Cr2O3 in magnetite = 3.51 wt. %
NWA 2787 Erfoud, Morocco200532S2, W330.5- magnetite: Cr2O3 = 3.9 wt. %;Al2O3 = 1.2 wt. % (photograph below)