[meteorite-list] Some further Four Corners tidbits

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Mon Jan 24 16:04:00 2005
Message-ID: <DIIE.0000002B0000318B_at_paulinet.de>

BUCHWALD V.F. (1975) Handbook of Iron
Meteorites (Vol. 2, 573-575, excerpts):

- polycrystalline, medium octahedrite with silicate-graphite inclusions
- anomalous, Group I
- 9.24% Ni, 0.54% Co, 0.15% P, 0.2% C
- 49 ppm Ga, 179 ppm Ge, 2 pprn Ir (for the metal phase)
- a mass of 25 kg was said to have been found
- shape of the meteorite was compared to a water-worn
  boulder with the extreme dimensions 26 x 26 x 16 cm
- upon cooling crystals developed an independent Widmanst?tten structure
- some grain boundaries are loaded with
  0.5-1 mm wide troilite and schreibersite veins
- kamacite shows indistinct Neumann bands
- some plessite fields have central areas of poorly defined haxonite*
- graphite is an important constituent
- schreibersite occurs as skeleton crystals
  and as grain boundary precipitates
- troilite is very common as grain boundary fillings and
  as fillings between the silicate- and graphite grains
- troilite is shock melted and solidified
- silicates occupy about 15% by area (olivines, pyroxenes, feldspar)
- mineral assemblage similar to that of Campo del Cielo
- Four Corners shows a certain structural analogy to Copiapo
- metallic portion of Four Corners related to Balfour Downs and Colfax
- silicate portion related to Balfour Downs and Campo del Cielo

*haxonite = (Fe,Ni)23C6


Best regards,

Bernd
Received on Mon 24 Jan 2005 04:03:58 PM PST