Ureilites
The ureilites are named for Novo Urei, a rural village in the Mordova
Republic, Russia, where several meteorites fell in late 1886.
The ureilites are subdivided into two groups: the monomict main group
and the less common polymict group. Main group ureilites are composed
largely of coarse-grained olivine and minor pyroxene, mostly in the form
of calcium-poor pigeonite, set in a dark carbonaceous matrix of graphite
and diamond, nickel-iron metal, and troilite. Our recent find, El Gouanem,
Morocco, is a rather typical member of the main group. Polymict ureilites
consist of a mixture of different lithologies. Besides clasts from main
group ureilites, they contain magmatic inclusions, dark carbonaceous
clasts, chondritic fragments of different origins, and various other
inclusions. This suggests a surface or regolith origin for the polymict
ureilites, an assumption that is supported by the values for noble gases
that have been implanted into the regolith by the solar wind.
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NWA 3223 Polymict Ureilite
Morocco, found in 2002
TKW : 51 gr
Physical characteristics:
The sample is a sub-rounded
stone with 60% fusion crust and soft when cut.
Petrography and mineral
compositions: (H. Takeda, Chiba and A. Yamaguchi, NIPR).
It is composed of medium to coarse (up to 1.6x1.2 mm in size)
olivine (Fo77-80, CaO = 0.3-0.4; Cr2O3
= 0.65-0.9 [both wt%; cores]) and pigeonite grains (Fs18.0Wo7.5;
Cr2O3 =1.1-1.3 wt%). Carbonaceous veins
typical of ureilites are observed at parts of the thin section and
dusty patches of fine-grained opaque minerals decorate the rims of
grains.
Classification: Achondrite
(ureilite, polymict); minimal shock with rare mosaicism in olivine.
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NWA 3223 -
00
12.59 gr
Nice slice of ureilite with crust on the edge !
$ 760 |
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NWA 3223 - 01
10.02 gr
Nice slice of ureilite with crust !
SOLD
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NWA 3223 - 02
7.08gr
Slice of Polymict ureilite with crust !
$ 430
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NWA 3223 - 03
6.25gr
Slice of nwa 3223 ureilite with crust on the
edge!
SOLD
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NWA 3223 - 04
4.04gr
An other slice of this special Ureilite with a low
TKW
SOLD
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