[meteorite-list] Owens Valley Iron 1913

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 10:22:33 2004
Message-ID: <DIIE.0000004C00000B67_at_paulinet.de>

> Hello list,

Hello Howard, Steve and List,

> Any articles about this too would be appreciated.

Here is part of what Buchwald offers in his trilogy on irons:

BUCHWALD V.F. (1975) Handbook of
Iron Meteorites, Volume 3, pp. 957-958:

Owens Valley, California, U.S.A.
Approximately 37=B0 28' N / 118=B0 0' W; 1800 m
Medium octahedrite, Om.
Bandwidth 1.15=B10.15 mm.
Recrystal-lized. HV 167 =B1 10.
Group IIIB. 8.60% Ni,
0.51% Co,
about 0.25% P,
21.5 ppm Ga,
45.9 ppm Ge,
0.15 ppm Ir.

History

A mass of 193.2 kg was found by a sheepherder in 1913, some 22 miles
northeast of Big Pine, Owens Valley, in Inyo County. It passed immediately
into the hands of Lincoln Ellsworth, the Arctic explorer, who in 1922 donated
the whole mass to the U.S. National Museum. Merrill (1922d) cut an end from
it and described it with excellent figures of the exterior and of etched slices.
Nininger (1933: figure 17) and Nininger & Nininger (1950: plate 5) reproduced
photographs of the exterior and of another, etched section. The meteorite is
erroneously listed as a coarse octahedrite in Hey's catalog (1966: 365).

Collections

Washington (157.7 kg main mass),
New York (32.63 kg endpiece),
Tempe (430 g),
London (277 g),
Paris (50 g).

Description

The elongated mass has the average dimensions 65 x 35 x 27 cm and weighs
193.2 kg. It is boldly sculptured, displaying several large bowl-shaped pits and
numerous smaller pits. The largest pits are 18 x 10 cm across and 9 cm deep;
15 x 10 cm across and 4 cm deep; and 13 x 13 cm across and 3 cm deep. The
smaller pits are 15-100 mm in diameter and 5-10 mm deep. Common to all these
bowls and pits are the sharp ridges that separate them. They are covered with
terrestrial oxides, 0.1-1 mm thick; and no fusion crust is visible. It appears that
the original regma-glypts are significantly modified by long exposure to weathering.

A minor part of the surface, 20 x 20 cm in area, appears to have survived the corrosion
relatively intact. The original regmaglypts here form low depressions, 25-35 mm in diameter
and 5-10 mm deep. They are separated by rounded ridges. In four places there are small,
hemispherical holes, 12-17 mm in diameter - presumably left after troilite had ablated away.
The fusion crust is, I believe, preserved in these holes, while the remainder of this part of the
surface is faintly checkered, reflecting the octahedral structure below. No cut through this part
has been made, but it seems to me that it represents a far less corroded part of the meteorite,
possibly the result of its projecting a few centimeters above the soil level. Etched sections show
a medium Widmanst=E4tten struc-ture of straight, slightly swollen kamacite lamellae with a width
of 1.15=B10.15 mm.

Taenite and plessite cover about 40% by area, partly as comb and net plessite, partly as black
taenite ... Schreibersite is present as 0.3-0.5mm wide and 5-10mm long lamellae; they are
monocrystalline but brecciated and enveloped in 0.6-1.5 mm wide rims of swathing kamacite.
The larger schreibersite crystals are frequently sheared and the shear zones are filled with
1-20 =B5 wide troilite veinlets.

Troilite occurs, in addition, as 2-15 mm rounded nodules, ... A few Reichenbach lamellae, typically
25 mm long and 0.01 mm wide and consisting of troilite with precipitated schreibersite flags, are
also present.

The overall impression of the etched sections is that of a structure which was plastically deformed
while still hot. Thereby the large schreibersite crystals were sheared and brecciated, and troilite was
squeezed into open fissures in the schreibersite and the metal. The metallic matrix, however, later
developed a normal, undistorted Widman-st=E4tten structure in which more phosphides precipitated.
The local, severe corrosion is mainly concentrated around the fissures - partially filled with troilite -
of the schreibersite and the metal.

Owens Valley has a primary structure corresponding to Aggie Creek, Baquedano and Cleveland.
Its secondary structure of recrystallized kamacite with finely dispersed taenite particles resembles
particularly Plymouth and Withrow. Chemically, it belongs to those meteorites that are transitional
between group IIIA and group IIIB.

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Received on Sun 01 Jun 2003 02:08:22 PM PDT