Does anyone on Orchid know how one might examine clay to detect
miscroscopic diamonds? What kind of microscope would help? Or other
device?
I really don’t know the answer for the question to YAFI below. But I
suspect that volcanic fields as we have here in BC might also be
diamondiferous and if so, a diamond-detecting microscope would help
us to find these vectors in the sub-soils of volcanic and glacial
dust.
PtP
Cross post removed
Does anyone on Orchid know how one might examine clay to detect miscroscopic diamonds? What kind of microscope would help? Or other device?
Peter, I don’t know if Canada has something like the USGS (United
States Geological Service), but I suspect they might. They will have
maps, background info of what the characteristics are in the field
for a particular type of stone and samples of the stone from the
field, usually for free or very low cost.
There are small, hand-held, battery operated, lighted microscopes,
ranging from 30X to 50X. They are sold in places like Radio Shack and
Edmund’s Scientific. Any over 50X definitely requires a table to
view, because hand-held devices will shake too much for you to focus.
Think of 50X binoculars. A 30X hand microscope costs under $10. It
should be more than adequate to pick up the diamondiferous crystals.
Here in Wyoming, we have diamondiferous ore. The last I heard they
had recovered around a dozen diamonds 1 ct. or over from their core
drillings (30 ft. deep) that were of gem quality. The largest was 5
cts. faceted in I color. A small sample from their core drillings,
about 2" x 3" cost me.25 cents U.S., about 15 years ago. Very small
diamonds are evident on the surface of the sample, and with a 30X
monocular you can see the diamond crystal shape.
The presence of diamond (or other heavy minerals) in soils or clays
is usually detected by a solid “fractionation” process. By using the
appropriate liquids, a suspension of the particles will resolve
itself into “layers” according to specific gravity. A centrifuge can
also be used to make the separations. It is quite rapid and
concentrates all the materials of similar specific gravity together
so that they can be more easily examined.
For true clay minerals, water will suspend the clay portion, all
other fractions will simply fall out. Examination with any decent
microscope will reveal the crystalline substances, easily separated
by shape or color, especially under crossed polarizers, just as with
thin sections. I’d suggest a short reading in the fundamentals of
petrography; the basics are not challenging.
Wayne Emery
I would think a simple filter such as Buchner flask with ceramic
sinter connected to a vacuum pump where the clay would be washed
away with water through the filter, leaving any such diamonds and
other mineral crystals behind to be identified by microscopy.
Helen
UK
Kimberlites do contain feldspar but more inportantly they are mostly
pyroxene and olivine. Some of the Russian diamond fields are rocks
called eclogites, which are only olivine and garnets. So how do you
spot your diamonds? the easiest way is by doing a heavy liquid
separation using TetraBromoEthylene otherwise TBE. The clay minerals
will float in the fluid and the heavy minerals will sink. Diamonds
have a specific gravity of about 4 and so will sink. You need to
look at the other heavies and try to identify them as well as this
will help tell what may be found even if you cannot see it. for
example, where platinum is found, the chemical composition of
chromites will be different to non-PGM host rocks. You will need to
get any garnets chemically analysed, probably by EDX and that will
give you a pointer to whether your kimberlite is diamondiferous even
if you dont find diamonds in your clay. Try doing a bit of panning in
the local streams, same way you would for gold. Again, garnets will
be the best pointer.
Best of luck,
nick
Thanks for the tip, Nick. Let’s say the kimberlite-clay is screened
so that only fine dust, barely visible at best, is treated with TBE.
Now if this works and the heaviest dust sinks irrespective of size,
expectedly there will still be a lot of dust crystals which are very
heavy. Here in BC for example, we have subsoil dusts which assay
high in various heavy metals like Ag, Bi and Mo. And yes, there may
be garnets etc. which sink as well.
The TBE method would concentrate the diamonds if it works as you say
below. But I think the final determination is a matter of
crystallography-microscopy is it not?
PtP
perhaps there is a university in your area of BC w/ith a geology
department. Ohio State University here in Columbus Ohio has a geology
dept. but i dont know anyone there you will need to get creative and
do some cold calling
best regards goo