D'Orbigny Angrite
Meteorite Name
Found 1979,  Argentina
Weathering &
Shock Level
Low weathering
mass of 16.65kg
Specimen Type
dpu thin section
A 16.55 kg stone, mostly covered with dark gray fusion crust, was found in a corn field after a
farmer hit it with a plow.  Classification and mineralogy (F. Brandstätter and G. Kurat, NHMV):
has a sub­ophitic texture, exhibiting laths of plagioclase (An>99, up to 2 mm) with subhedral to
euhedral augite and anhedral to subhedral olivine; augite shows marked optical zoning, with
cores containing 1.6 wt% TiO2, 7.8 wt% Al2O3, XMg [Mg/(Mg + Fe + Ca)] = 26.8 mol%, XFe
= 21.9 mol%, and XCa = 51.2 mol%, and reddish-brown rims with 4.0 wt% TiO2, 8.0 wt%
Al2O3, XMg = 0.6 mol%, XFe = 46.7 mol%, and XCa = 52.6 mol%; olivine is zoned, with
cores having Fa39.7La1.3 (La = larnite), 0.9 wt% CaO, 0.13 wt% Cr2O3, 0.45 wt% MnO, and
rims having Fa75.9La11.5, 6.6 wt% CaO, 0.12 wt% Cr2O3, 0.93 wt% MnO; in places,
anhedral kirschsteinite (Fa62.0La34.0, 20.0 wt% CaO, 0.11 wt% Cr2O3, 0.75 wt% MnO) is
intergrown with olivine; in places, abundant ultrabasic glass fills pore spaces (SiO2 ≈40 wt%);
minor to accessory phases include transparent brownish spinel (up to 500 µm), ulvöspinel,
troilite, and a silicophosphate; contains abundant round vugs, up to 2.3 cm in diameter, and
druses containing augite and rare centimeter-sized green olivine crystals (Fa9–11); rock is
fresh, but pores contain variable amounts of caliche. Specimens: main mass with finder;

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Copyright 2008
Copyright 2008
Copyright 2008
Copyright 2008