[meteorite-list] News on NWA

From: M come Meteorite Meteorites <mcomemeteorite2004_at_meteoritecentral.com>
Date: Mon Mar 21 13:24:53 2005
Message-ID: <20050301162347.19970.qmail_at_web50102.mail.yahoo.com>

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: mcomemeteorite2004_at_yahoo.it
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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Received on Tue 01 Mar 2005 11:23:46 AM PST