GRA 98108

GRA 98108

Macroscopic Description: Kathleen McBride
The exterior surface of this meteorite has small patches of rough, black fusion crust (5% of surface area).  The exposed interior is yellowish-green, coarse-grained olivine crystals.  There are some areas that appear to be rust stained or have rootbeer (pyroxene?) colored minerals.  The olivine crystals are opaque to transparent.  Freshly broken faces show transparent, white crystalline (plagioclase?) material with coarser-grained olivine.  Single grains are several mm in length.  Individual crystal faces are visible as well as cleavage planes.  There are several rusty areas where minerals are stained.  Maroon colored minerals and small black specks are distributed throughout the rock.

Thin Section (, 5) Description: Tim McCoy
The section contains both finer-grained (0.2-0.5 mm grain size) equigranular areas of olivine, orthopyroxene and rare plagioclase with 120º triple junctions, and coarser (up to 5 mm) grains of orthopyroxene and olivine intergrown with ragged boundaries.  Orthopyroxene is the more abundant phase.  Olivine is Fa₂₇, orthopyroxene is Fs₂₂Wo ₂ and plagioclase is An₈₉.  The Fe/Mn ratio is ~27.  Opaque phases comprise only a few percent of the rock and include troilite, chromite and rare metal.  It is moderately shocked.  It is an unusual achondrite, and is most likely an olivine diogenite.