[meteorite-list] Graphite Nodules

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 23 Nov 2007 16:58:39 UT
Message-ID: <DIIE.0000009A0000231A_at_paulinet.de>

Hello D & K, Hi List,

"...has anyone found nodules from other iron meteorites ...?

I haven't but Vagn Buchwald has found them in several irons:

1. Butler (IRANOM):

Figure 402. Butler (Tempe no. 137ax). Plessitic octahedrite with an anomalously
high germanium content. Large troilite nodule (gray) and three graphite nodules*
(black). Deep-etched. Scale bar in cm. (Courtesy C.B. Moore.)

* The nodules are very small, about 0.5 mm

Figure 407. Butler (Copenhagen no. 1876, no. 2247). The edge of a graphite nodule,
composed of micron-sized crystallites. Numerous metal particles are present along
the edge. Polished. Scale bar 40 ?.

2. Cosby's Creek (IAB):

Most specimens appear to be broken fragments; concave smooth impressions of now
lost troilite-graphite nodules, 2-5 cm in size, are often found in the fracture
surfaces.

Graphite is common, probably always associated with troilite. Reichenbach (1862b: 57)
isolated a graphite nodule weighing about 80 grams, and J.L. Smith (1876a) examined a
graphite nodule 6 x 3.5 x 2 cm weighing 92 g. A discontinuous rim of 1 mm troilite covered
the surface of the nodule, and in the interior other minor troilite bodies were present.
Smaller graphite and troilite nodules are frequently met with. Some appear to have been
parallel, elongated cones of finger size that were easily detached from the matrix. In U.S.
National Museum no. 738, the remnants of a complex troilite-graphite-schreibersite-cohenite
nodule may be seen.

Mazapil (IAB):

Both Hidden and Brezina noted the prominent troilite-graphite nodules which appeared
in slight relief on the surface and may be indistinctly seen upon the engraving provided
by Hidden. Perhaps they are seen somewhat better in a photograph reproduced by Merrill
(1929: plate 6).

The plessite morphology and the troilite-graphite nodules indicate a close relationship
to Misteca, Balfour Downs and Shrewsbury, particularly to the last mentioned, ...

Reference:

BUCHWALD V.F. (1975) Handbook of Iron Meteorites, Volumes 1-3.


Best wishes,

Bernd
Received on Fri 23 Nov 2007 11:58:39 AM PST