jeff
At 11:23 AM 3/1/2005, M come Meteorite Meteorites wrote:
Hello
I have finaly received the analysis of many of my NWA, this is some special entry exit in the new Met.Bulletin
NWA 903
� Found 2003 � Ordinary chondrite H3
Several stones were bought at Erfoud market by an anonymous buyer. Classification and mineralogy (G.Pratesi, V.Moggi-Cecchi, A. Salvadori, MSP: petrography and EMPA; G. Sighinolfi and S. Lugli, UMo: EMPA): the meteorite consists of chondrules 300-600 �m in size, of different types (PO, POP, BO, RP) and their fragments embedded in a fine-grained matrix; olivine is Fa1.62-35.17, with an average of Fa14.85; olivine compositions vary continuously between these two values. The mean value and the amount of Fe,Ni alloy suggest a classification as H chondrite. Low-Ca pyroxenes range from Fs4.26En92.95Wo1.34 to Fs17.36En82.16Wo0.48. A diopsidic pyroxene (SiO2 50.57, Al2O3 10.49, MgO 9.99, CaO 7.98 wt. %; SiO2 49.80, Al2O3 1.79, MgO 20.48, CaO 1.25 wt. %) has been found, too. Minor phases are kamacite, taenite and troilite; some olivine grains in BO and PO chondrules are markedly zoned and contain a glassy mesostasis. Compositional data on olivine point to a petrological subtype <3.5. Weathering grade is W3; shock stage is S1. Specimens: one thin section and 28.9 g, MSP; main mass (500 g) with anonymous buyer.
NWA 1054
� Morocco � Found 2001 � Acapulcoite
A stone of 86 g was bought in Erfoud (Morocco) by an anonymous dealer. Classification and mineralogy (G.Pratesi, V.Moggi-Cecchi, L. Mancini, MSP: petrography and EMPA; G. Sighinolfi and S. Lugli, UMo: EMPA): either thin section and type specimen sample look to be composed by a fine grained aggregate. In thin section it displays an granular texture with grains mainly represented by olivine, pyroxene, Fe,Ni alloy and troilite and ranging from 200 to 700 �m in dimensions. Olivine is homogeneous and has a typical forsteritic composition, (Fa = 6.37 mol %); orthopyroxene is bronzitic (Fs = 7.77, Wo = 1.32 mol %). High Ca-pyroxene (Fs = 3.33, En = 51.23, Wo = 45.44, Al-Px = 1.50 mol %) and plagioclase (An = 14.27, Ab = 79.47, Or = 6.25 mol %) are also common. Apart from silicates, major phases are metal and troilite. Accessory phases include Na-Merrillite and magnesiochromite (Cr/(Cr+Al) = 0.96; Fe:Mn:Mg ratios = 0.60:0.12:0.28). Nichelphosphide grains with an anomalous composition, pointing to a (Ni,Fe)4P formula have been found, too. This meteorite shows a recrystallization texture with abundant 120� triple junctions and many interstices filled with metal. Based on texture (fine coarsed), mineralogy and chemistry (Cr content of diopside varying from 1.17 to 1.35 wt. %) the meteorite is classified as an acapulcoite. Terrestrial weathering grade is rather low (W1); optical features (sharp extinction of olivine) indicate that the sample is very weakly or not shocked (S1). Specimens: main mass with buyer; type specimen (17.9 g) and thin section, MSP.
NWA 1807
� Morocco � Found 2002 � Carbonaceous chondrite (CV3)
A stone of 274 g was bought in Erfoud (Morocco) by Mr. Matteo Chinellato. The main mass, weighing 54.5 g, has no crust. Classification and mineralogy (G.Pratesi, V.Moggi Cecchi, MSP): a cut surface on the type specimen displays rather large chondrules and some small white spots. In thin section many chondrules of various kinds (POP, PO, BO, RP) accounting for ~50% vol. and ranging from 500 to 1200 �m are visible, set in a fine intergrowth of microporphyric orthopyroxenes. Olivine composition ranges from Fa0.83 to Fa5.03 mol. % in the chondrules and reaches Fa49.72 out of them. Orthopyroxene is enstatitic (En98.14, Wo1.06). An augitic pyroxene is also present (Fs15.54-28.61, En25.12-36.97, Wo46.12-47.49). Chondrules glass is anorthitic (An84.67, Ab15.3 mol. %). Fe,Ni alloy and troilite are rather uncommon (less than 5% vol.). Rare apatite grains and CAIs are present. Oxygen isotope measurements (I.Franchi, R.Greenwood, Open University) d17O = -1.643� d18O = 2.524�; D17O = -2.955� plot on the end of the CV range. Based on texture, mineralogy, chemistry and OI data, the meteorite is classified as a CM2 carbonaceous chondrite. Terrestrial weathering grade is rather low (W1); optical features indicate a low shock stage (S1). Specimens: main mass with buyer; type specimen (20.5 g) and thin section, MSP.
NWA 1808
� Morocco � Found 2002 � H5, impact melt breccia
A dark brown stone of 684 g was bought in Erfoud (Morocco) by an anonymous buyer. Classification and mineralogy (G.Pratesi, V.Moggi Cecchi, MSP): the main mass has no crust and a large metal vein on its surface. A cut surface on the type specimen displays areas with a marked difference in the amount of metal and seems to be composed by two different portions: a fine grained one and a coarse grained one. In thin section the fine grained part shows a re-crystallization texture with few grains of residual metal and olivine in a matrix of feldspatic glass (An = 17.62, Ab = 77.49, Or = 4.88 mol. %) containing very fine grained olivine and pyroxenes crystals; metal pools and droplets shows fringes substituting the outstanding glass. The coarse grained portion presents a typical chondritic texture: major phases are olivine and low-Ca pyroxene (Fa = 18,96 mol. %; Fs = 16,31, En = 82,03, Wo = 1.67 mol %), metal and troilite. Based on texture, mineralogy and chemistry of the coarse grained portion, the meteorite is classified as an H chondrite impact melt breccia. Terrestrial weathering grade is absent (W0); optical features (undulatory extinction of olivine) indicate that the sample is rather distinctly shocked (S3). Specimens: main mass with buyer; type specimen (20.1 g) and thin section, MSP.
NWA 2045
� Found 2003 � Ordinary chondrite LL3
One stone weighing 19 g was bought at Erfoud market by an anonymous buyer. Mineralogy and classification (G.Pratesi, V.Moggi Cecchi, MSP)): the meteorite consists of chondrules 500-700 �m in size, of different types (PO, POP, BO, RP) and their fragments embedded in a fine-grained matrix; olivine is Fa29.83-43.73, PMD 22%, the average is Fa35.64; mean low-Ca pyroxene is Fs24.87En73.57Wo1.57; minor phases are pigeonite, (Fs9.40En45.72Wo44.88), augite, kamacite, taenite and troilite; POP and PO chondrules are moderately zoned and contain a glassy mesostasis. Compositional data on olivine point to a petrological subtype 3.8/3.9. Weathering grade is W3; shock stage is S2. Specimens: one thin section and 3.7 g, MSP; main mass with anonymous buyer.
NWA 2179
� Found 2003 � Ordinary chondrite H3
Several stones weighing in total 367.2 g was bought at Erfoud market by an anonymous buyer. Mineralogy and classification (G.Pratesi, V.Moggi Cecchi, MSP)): the meteorite consists of chondrules 500-700 �m in size, of different types (PO, POP, BO, RP) and their fragments embedded in a fine-grained matrix; olivine is Fa0.81-18.38, with an average of Fa6.68; two clusters of analyses, with mean values at Fa1.53 and Fa12.02, respectively, can be delineated for chondrule olivines, pointing to a classification as H chondrite. Low-Ca pyroxenes range from Fs6.13En93.07Wo0.80 to Fs21.01En78.17Wo0.83, in good agreement with olivine data; minor phases are pigeonite, kamacite, taenite and troilite; some olivine grains in BO and PO chondrules are markedly zoned and contain a glassy mesostasis. Compositional data on olivine point to a petrological subtype <3.5. Weathering grade is W2; shock stage is S1. Specimens: one thin section and 29.4 g, MSP; main mass (88.8 g) with anonymous buyer
NWA 1052
� Morocco � Found 2001 � Acapulcoite
A stone of 22 g was bought in Erfoud (Morocco) by Matteo Chinellato. Classification and mineralogy (G.Pratesi, V.Moggi-Cecchi, L. Mancini, MSP: petrography and EMPA; G. Sighinolfi and S. Lugli, UMo: EMPA): either thin section and type specimen sample look to be composed by a fine grained aggregate. In thin section it displays an granular texture with grains mainly represented by olivine, pyroxene, Fe,Ni alloy and troilite and ranging from 200 to 700 �m in dimensions. Olivine is homogeneous and has a typical forsteritic composition, (Fa = 5.95 mol %); orthopyroxene is bronzitic (Fs = 7.60, Wo = 1.44 mol %). High Ca-pyroxene (Fs = 3.63, En = 51.11, Wo = 45.26, Al-px = 1.44 mol %) and plagioclase (An = 13.73, Ab = 79.90, Or = 6.37 mol %) are also common. Apart from silicates, major phases are metal and troilite. Accessory phases include Na- and Ca-Merrillite and magnesiochromite (Cr/(Cr+Al) = 0.91; Fe:Mn:Mg ratios = 0.58:0.09:0.33). Nichelphosphide grains with an anomalous composition, pointing to a (Ni,Fe)4P formula have been found, too. This meteorite shows a recrystallization texture with abundant 120� triple junctions and many interstices filled with metal. Based on texture (fine coarsed), mineralogy and chemistry (Cr content of diopside varying from 1.18 to 1.43 wt. %) the meteorite is classified as an acapulcoite. Terrestrial weathering grade is rather low (W1); optical features (sharp extinction of olivine) indicate that the sample is very weakly or not shocked (S1). Specimens: main mass with buyer (Matteo Chinellato); type specimen (4.7 g) and thin section, MSP.
Take a look at 1 hour to this link http://it.geocities.com/mcomemeteoritecollection/nwa.html for the other classifications.... pieces of this meteorites its available, not the NWA 1807
Matteo
===== M come Meteorite - Matteo Chinellato Via Triestina 126/A - 30030 - TESSERA, VENEZIA, ITALY Email: [EMAIL PROTECTED] Sale Site: http://www.mcomemeteorite.it Collection Site: http://www.mcomemeteorite.info International Meteorite Collectors Association #2140 MSN Messanger: spacerocks at hotmail.com EBAY.COM:http://members.ebay.com/aboutme/mcomemeteorite/
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