diamonds just are not going to be produced by a blow torch, cubic
carbon crystals may be produced.
Thank you for the reply. I am attempting to summarize the UCD theory
as it is presented in the literature and it would help if other
discussants would also give citations for their arguments. Hausel
provides a 100 page overview at gemstonebookstore.pbworks.com. He
calls it a "whole new concept in exploration for diamonds worldwide".
But the nature of that new concept is only beginning to emerge. That
is why we are having this discussion.
I posted the Jem Stansfield BBC video on Orchid. He used a blow
torch and produced diamonds unless Dr Mark Newton at Warwick U was in
error about the Raman 1332 frequency and his declaration that Jem had
truly produced diamond. The grade and size of the diamond is not at
issue any more than the Discovery TV demonstration of blowing up a
barrel containing graphite which then became diamond. Mother Nature
has immeasurably greater resources and time to come up with bigger
and better stones.
When Nick Royall says "show us the diamonds", I refer to examples as
above. If you also google "graphitized diamond" you can connect with
the Korsakov et al article from Journal of Petrology 2010 which
shows pictures of "graphite coatings around diamonds". I found Figure
1 and Figure 6 (c) to be especially helpful. The latter,
interestingly is diamond within Mg-Ca which is within graphite. The
authors state that "carbonates could produce carbonate melts and this
could be very important for diamond formation". Could the inner
diamond crystal then originate in an Mg-Ca carbonate?
Likewise the NR statements that "the term graphitized diamonds is
meaningless - just graphite would have done" and "metamorphism would
not turn diamonds to graphite" are not in accord with well
established science on UCD. I pointed that out by citing another
study of graphitized diamond previously. Korsakov is a second and
there are others.
The placer gold emplacement analogy is quite correct.
All I was referring to with this analogy is that if you find
diamonds, no matter how small or in whatever host rocks, that is of
prospecting interest because it causes you to generate a theory about
their origin. Some of the microdiamonds in Korsakov et al are as
small as 25 microns (25/1,000 mm). I expect there were much smaller
ones as well but they were to difficult to analyze. If however one
finds 1 micron diamonds that will still be of great prospecting
interest. When I prospect for gold, if I find 2x earth crust average
at 5 ppb I wonder if higher grade ore is nearby. But ANY finding of
diamond, no matter how small, is of interest.
Some of the largest Nambian diamond deposits are being mined at the
ocean shoreline, where dikes and pumping make access to the correct
layers available. However, these diamonds (some gem quality) were
not formed in the sedimentary environment. They have been weathered
and eroded from a metamorphic site upstream from the deposit.
I have never denied that where diamonds are found and where they are
formed are two different matters. Finding diamonds in some surprising
places is the UCD theory as I understand it. Then we speculate on how
they got there and over time try to turn the speculation into more
verifiable fact and theory. Korsakov et al in the Petrography section
refer to diamonds from "calc-silicate rocks(impure marbles and garnet
clinopyroxene) and gneisses". Diamonds FOUND in marble and gneiss -
why not phyllite, schist, or even serpentinite and amphibolite?
There seems to be some difference of opinion in usage of the word
ophiolite. NR says "the simple word for these ophiolite complexes is
serpentine" and "ophiolites are not metamorphic rocks". As I have
said many times, when cultures with very different histories in
mineralogy and gemology meet (eg Chinese and Western English) it
helps when we clarify how we are using words: wiki/Ophiolite says
ophiolite is "a section of the Earth's oceanic crust and the
underlying upper mantle that has been uplifted and exposed above sea
level" and wiki/Serpentinite says "metamorphic transformation of
ultramafic rock from the Earth's mantle". A serpentinized ophiolite
would then be a metamorphic rock.
If the wiki definition is correct usage, then the ophiolite
originally is oceanic crust which could be a mix of sediments as well
as igneous and metamporphic rock AND the upcoming mantle rock which
we think is a likely origin of diamonds because of extremes of both
temperature and pressure.
But it may clarify the matter to talk about an ophiolite ENVIRONMENT
on its long journey to mountain formation on the surface, eg west
coast of North America. Diamonds originating in the mantle under
ultra-high pressure, ie UHPM conditions are partially replaced by
graphite (Korsakov et al cite four other reports to directly support
their findings on this). I am at a loss though to understand how
"metamorphism would not turn diamonds to graphite but dissolve them
and they would form carbonates" (NR). How does this transforming
(metamorphic) mechanism work as diamonds dissolve and how does the
solution become a carbonate? Maybe a few steps are needed to explain
Whatever the transforming mechanism why should the graphitized
diamonds stay in one place? IMO this is the essence of UCD theory. In
prospecting we try to come up with some ideas on where the diamonds
in the diamond-graphite mix originated and whether it might point to
a nearby economic find. Hausel is clear that no economic find has yet
***** If you have an ultramafic surface formation which originated in
the mantle and upper crust and it is now located in a complex
environment and you find graphite in that environment (perhaps in
phyllites, schists and calcite/dolomite/marbles), would you not want
to test the graphite for microdiamond nuclei regardless of the kind
of rock in which it is located? That is the practical prospecting
issue for myself, Rock9 and others. Your opinion is appreciated. *****
Humble graphite becomes a much more interesting mineral then as a
diamond indicator in UCD theory to validate Hausel as part of "a
whole new concept in diamond exploration worldwide". The Aububon
Field Guide says graphite is found in "schists of regional
metamorphic rocks and in marble". (page 350).