[meteorite-list] DIAMOND IN THE CANYON DIABLO IRON

From: Steve Schoner <steve_schoner_at_meteoritecentral.com>
Date: Thu Apr 22 10:25:43 2004
Message-ID: <20030523044343.74681.qmail_at_web12708.mail.yahoo.com>

I have in my collection, one nice iron with a black
diamond cluster visible on a sandblasted surface.

I attempted to blast what I thought was a thick
coating of oxide off the specimen. As I did so on the
piece, I found that the crystal structure became very
evident in bold relief.

In the center of one of these faces where the crystals
were very apparent was what I thought to be residual
oxide.

I attempted to sand blast it away, and still it
remained sticking out of the matrix.

I was amazed, and getting my hand lens examined the
spot closely. I could not believe my eyes... as I saw
the tiny crystal face, very black and quite distinct.

It was a genuine Canyon Diablo black diamond cluster.

I still have the piece in my collection.

I might, if I can get my digital camera in close
enough to take a picture of it, post it on my site for
all to see.

Steve Schoner
http://www.geocites.com/meteorite_identification


--- Robert Verish <bolidechaser_at_yahoo.com> wrote:
>
http://www.minsocam.org/msa/collectors_corner/arc/diamondm.htm
>
> American Mineralogist - Volume 24, pages 677-680,
> 1939
>
>
> IDENTIFICATION OF DIAMOND IN THE CANYON DIABLO IRON
>
> C. J. KSANDA, Geophysical Laboratory, Carnegie
> Institution of Washington, and E. P. HENDERSON,* U.
> S.
> National Museum, Washington, D. C.
>
> The first good evidence of diamond in a known
> meteorite was published in 1888, by Jerofejev and
> Lacbinov.(1) In a stony meteorite which fell in
> September 1886, near Novo-Urei, they found grayish
> grains which were regarded as diamonds. Kunz(2) was
> able to procure a small piece of the same meteorite
> and substantiated their conclusion.
>
>
> FIG. 1. Section of Canyon Diablo meteorite showing
> the
> area in the center of the meteoritic iron from which
> the diamonds were removed.
>
> In 1891 Foote(3) reported hard particles in the
> Canyon Diablo iron. Much. subsequent work in which
> the
> mode of occurrence and general crystallographic
> appearance of these grains are described, is
> reviewed
> by Farrington.(4)
>
> Recently small black grains embedded in a slice
> from a Canyon Diablo iron have been identified by
> means of the x-ray powder spectrum method and by
> microscopic examination as diamonds. The specimen
> containing these diamonds was purchased by the U. S.
> National Museum from H. H. Nininger, Denver,
> Colorado,
> who while cutting the specimen found small dark
> inclusions that resisted the saw, and assumed that
> they were diamonds. The section of iron shown in
> Fig.
> 1 is 115 mm. long, 55 mm. wide at its widest part,
> and
> weighs 411.7 grams. The specimen was not further
> polished in the U. S. National Museum laboratories
> because to do so would probably grind away several
> of
> the small diamonds visible to the naked eye.
>
>
>
> FIG. 2. The cavity enlarged 6X, containing black
> diamonds, showing larger individuals lining the
> inner
> wall, securely embedded in graphite. Arrow points
> indicate the location of larger grains of black
> diamonds partly excavated.
>
> The diamonds occur associated with some
> graphitic
> material within a troilite area. Immediately
> surrounding the troilite is a series of irregular
> areas of schreibersite. A wax dam was constructed
> around the area and the diamonds were freed by
> repeated treatments of nitric and hydrochloric acid.
> The insoluble residue was washed out and saved. This
> residue was slightly contaminated with some organic
> matter as the acid reacted with the wax dam. The
> black
> grains were repeatedly boiled with mixed acids and
> the
> acid soluble portion decanted off and rejected.
>
> About 50 individual black grains were recovered
> whose sizes vary from 0.1 to 0.6 mm. The cavity made
> by the acid (see Fig. 2) is lined with larger
> individuals securely embedded in the graphite and
> troilite. Several of these black grains were removed
> by working them out with a needle point. The largest
> was 0.9 mm. in diameter.
>
> The grains resemble the black diamond, or
> carbonado, of commerce. Under the microscope they
> are
> black, and as recovered are porous, and therefore
> seem
> to consist of minute individuals. A rude layering
> appears in the larger grains. They are more easily
> broken down than ordinary black diamond.(5)
>
> Grains rubbed between two pieces of ordinary
> black diamond did not produce any scratches visible
> with the microscope.
>
> X-ray analysis. Crushed particles were mounted
> on
> a fine thread by means of a film of vacuum grease
> and
> a photograph was taken with Cu-K radiation in a
> circular camera of an effective radius of 57.2 mm.
> The
> specimen was rotated uniformly during the exposure.
> The results of the x-ray analysis are given in Table
> 1. The diffraction pattern shows only the lines
> theoretically possible within the angle of
> reflection
> with Cu radiation for the cubic lattice of diamond.
> The systematically absent reflections are
> characteristic of the face-centered lattice type of
> diamond. The unit cell dimension, do=3.557,
> calculated
> from spacings d/n is in agreement with previously
> published data.(6)
>
> X-ray powder photographs of the graphitic mass were
> also taken. The resulting diffraction pattern shows
> a
> large number of lines,7 not all of which could be
> identified. Of the 16 lines measured on the film,
> only
> nine are identical in position and intensity with
> the
> first nine lines of the known graphite structure.(8)
>
> No lines characteristic of diamond were found on
> these
> films.
>
> Optical properties. Under the microscope, in a
> melt of sulfur and selenium, most crushed grains
> were
> not transparent except in irregular patches at thin
> edges, where they were isotropic; n for orange
> colored
> light is greater than 2.37 and for yellow light
> about
> 2.42.(9)
>
> * Published by permission of the Secretary of the
> Smithsonian Institution.
>
> 1) Jerofejev, M., and Lachinov, P., Zapiski
> Mineralogicheskoe Obshchestvo, Leningrad, (2) 24,
> 263-294 (1888).
>
> 2) Kunz, G. F., Science, 11, 118-119 (1888).
>
> 3) Foote, A. E., A new locality for meteoric iron
> with
> a preliminary notice of the discovery of diamonds in
> the iron: Am. J. Sci. (3), 42, 413-417 (1891).
>
> 4) Farrington, O. C., Meteorites; their Structure,
> Composition and Terrestrial Relations. By author.
> Chicago, 1915.
>
> 5) Black diamonds (or carbonado) such as those used
> for industrial purposes consist usually of a very
> compact mixture of gray to black and translucent
> white
> particles in various proportions, intimately
> intergrown. The individual crystals are of
> microscopic
> size, and the structure when fractured is
> fine-grained.
>
> 6) Wyckoff, R. W. G., The Structure of Crystals, 2nd
> Ed., Chemical Catalog Co., Inc., New York, 1931.
>
> 7) The specimen appeared slightly altered by
> previous
> treatment and etching of the cavity with acid.
>
> 8) See, for example, Hofmann, U., and Wilm, D.,
> Zeits.
> f. Elektrochem., 42, 504-522 (1936).
>
> 9) The optical properties were determined by Dr. H.
> E.
> Merwin, and his aid in this investigation is
> gratefully acknowledged.
>
>
>
> __________________________________
> Do you Yahoo!?
> The New Yahoo! Search - Faster. Easier. Bingo.
> http://search.yahoo.com
>
> ______________________________________________
> Meteorite-list mailing list
> Meteorite-list_at_meteoritecentral.com
>
http://www.pairlist.net/mailman/listinfo/meteorite-list


__________________________________
Do you Yahoo!?
The New Yahoo! Search - Faster. Easier. Bingo.
http://search.yahoo.com
Received on Fri 23 May 2003 12:43:43 AM PDT