Leaming’s book on jade refers to experiments in Russia under Dr.
Medvedev to enhance jade and semi-jade using heat and pressure
(200-500 C and 500 bars).
Does anyone have up-date on these experiments? Leaming
suggests that the basic process works but excessive heat has the
opposite effect.
Since most jade mined is low grade and may even be called
"semi-jade" (Leaming’s word), some way to rescue it from the waste
dump would seem desirable.
44 Kinds of Jade?
Leaming describes Yang Han Chen as an expert on jade and then says
Yang refers to 44 (not 2) different kinds of jade in his book (title
not given). I googled around but could not find this book which
Leaming says is now available in English. Does anyone on Orchid have
a lead on it?
Just an FYI, Chinese consider many green stones as ‘jade’.
Therefore, it does not surprise me that Yang describes many ‘kinds of
jade’. Would be interested in seeing his book.
Cheers from Don in SoFL
Jade is one of those commonly used, but imprecise names. Generally
only two minerals are considered to be jade - jadeite and nephrite.
Many purist only consider jadeite as jade. Their are a lot of
"named" varieties, but all fall under the two minerals. There also
are a lot of the usual marketing tricks used to promote jade like
material. You won’t confuse really good jade with any thing else…
Maybe really good chrysoprase for color. Nothing else has the real
jade look… I am sure there is a term for this which escapes me at
the moment.
I acquire a small amount of “blue” jade out of California in the 70’s
and would love to find the source. I have gotten some interesting
stuff out of CA that us called “blue”… None of it really blue…
More greyish. Would love to find more if anyone knows a source. I
only had a small piece and made a lovely ring for my girlfriend at
the time… She is gone, but I still pine for the jade:)
Those old farts among us know one needs to grab things as you can.
I’d give anything to travel back in time and be able to buy some of
the gem silica that was coming out of Arizona in the 70’s… Or
that good Chysoprase from down under. There are a lot of things that
are much rarer than diamonds… And in my humble opinion more
beautiful.
Just an FYI, Chinese consider many green stones as ‘jade’.
Therefore, it does not surprise me that Yang describes many ‘kinds of
jade’. Would be interested in seeing his book.
Leaming runs into a diplomatic problem when it comes to defining
jade. If he defines it too rigorously he may offend some Chinese (and
other) experts. Also, though he may have been seen as Canada’s senior
jade expert, it’s a big world out there so due modesty is called for.
But don’t get me wrong. I would recommend Leaming’s book highly.
Perhaps it is not suprisingly though that he does not come out and
give a succint definition for jade as you find in online geology
dictionaries. IMO the solution is not “buyer beware” so much as that
the buyer should be more demanding. Why not for example a “batch
assay” of jade material used in a given supply of let us say jade
beads? If you want to use jade as floor tile, would it not be wise to
have results of compression-testing? Even with the Northern BC Dease
Lake area jade I am seeing considerable variation in what is going to
market.
Leaming even leaves some room for using actinolite-tremolite as the
necessary minerals in jade. On page 172 he says the “pure” forms of
these minerals range in theory from 0% Ca to 0% Mg. But would it be
jade with 0 Mg or 0 Ca? Also, he talks about heat successfully
enhancing the jade up to a stage after which there is the opposite
effect. But heat drives off the water bonds. Is it still jade by
definition without OH? Does anyhydrous jade stay within the
definition?
If anyhydrous jade is allowed, why not jade glaze (ie glaze made
with jade powder) for pottery? Nick may have an opinion on that
further to his comment that when the Chinese set out to make jade,
they ended up with porcelain. But pottery glazes can incorporate
various minerals so why not jade minerals at least as part of the
mix? IOW can you get “jade green” on pottery by using a jade glaze?
at Jade Cove, north of Big Sur. I was there a couple of times. The
local Jade society has a show in October and November. There are
several places up and down the coast that a person can get Jade and
Moonstone. Near Eureka, Calif. there is place that a person can get
Black Jade, with pyrite imbedded in the stones.
Veva Bailey
One of the problems with characterising jade is hat there are 2
distinct mineral types which are actually very different, jadeite
and nephrite. Jadeite is a pyroxene group mineral, which in its
chemically purest form is sodium aluminium silicate and is white. The
colouration is caused by impurities of Ca, Mg, and Fe. If you had a
pure form of Ca “jade” it would be a mineral called wollastonite,
CaSiO3. Nephrite jade has a small amount of water of crystallisation,
as do other amphiboles. They are similar to the pyroxene group
minerals in many ways but they are a different group.
Heating jade to enhance it will have different effects on the 2
mineral types/groups. You wll not heat an amphibole enough to remove
the hydroxyl ion without changing it entirely so you dont get
anhydrous jade any more than you get anhydrous asbestos. So, can you
create a jade glaze? Jadeite requires pressure s well as heat to form
so the answer there is no. You can make wollastonite quite easily but
not as a glaze on ceramic because it will chemicaly ract to form
something else. A glaze is a glass, but do not confuse this with
domestic glass. You can crush jadeite to make a glaze for pottery,
but would be better off using feldspar as it is cheaper, more common
and has a lower melting point. The colour of glazes is normally due
to metal oxides added on purpose. The reasn minerals are added to a
glaze mix is for thermal fit. Glasses as we use them have a much
higher coefficient of expansion ad as such dont stick to a ceramic
body at room temp. You can add jade to a glaze, you can made jade
green glaze (odd how the colour is agreed upon when it isnt actually
jade we are talking about) but you cannot make a jade glaze on a
ceramic body.
You can make gold but to do so you need an equal amount of platinum
and a nuclear reactor. By bombarding the platinum with very high
energy radiation you can create gold by adding the proton needed.
Unfortunately your gold is radioactive and costs you billions.
Nick
What if I define a jade ore body as simply an ore containing the
mineral actinolite?
Whether the product of that ore meets the criteria of jewellers and
carvers and other stone cutters is another matter and perhaps that is
where most of the imprecision comes in. How the
fibers/crystals/needles have grown etc determines the outcome for
practical usage. Thus the imprecision is only a problem in that we
have a diversified product (like diverse kinds of soap) which
requires clear labelling. In the words of Mao in a Confucian moment,
“Let one hundred flowers bloom”.
In western words the imprecision is just a matter of the criteria
you need for your particular product.
At the same time there seems to be imprecision in the chemical
formula itself which I find more problematic. The Audubon Field Guide
gives the same formula for actinolite and tremolite (both are a
silicate which also bonds water, Mg, Ca and Fe). But the CAS codes
actinolite and tremolite very differently. Tremolite has no Fe.
Audubon OTOH says actinolite only has more Fe but both have Fe.
Leaming says that the difference is Mg and Ca with pure tremolite
having no Mg and pure actinolite having no Ca. Leaming also talks
about research on heating which enhances jade and I expect that
drives off at least some of the water bonds and yet it is still
called jade.
Your opinion?
You wll not heat an amphibole enough to remove the hydroxyl ion without changing it entirely so you dont get anhydrous jade any more than you get anhydrous asbestos.
I gave the two page references from Leaming in which he talks about
heating jade (nephrite) to enhance it.
He is talking about heat which is within the range of a standard
pottery kiln. It is not clear if the container must also be closed as
I gather the GE containers are which make jadeite. Leaming does say
the heat enhancement increases hardness and given that one criterion
of a gem stone is durability, this is definitely an enhancement.
Closed containers would prevent the OH bond from being driven off.
Leaming says to simply heat jade in a test tube and you can see the
water condensing on the sides. Does it then cease to be jade? Your
opinion is yes. My query though has to do with the general model of
chemical changes which would make jade into something better, ie
enhancing it by both gemmological criteria of beauty (eg colour) and
durability (hardness and perhaps even toughness). GE enhancement in
lab-created stones may also have an effect on the third criterion of
rarity.
The “general model” of enhancement has to do with both chemical
changes and structural changes in crystal growth. The latter first.
That is what I meant earlier by “physical chemistry”, awkward as the
expression may be. I have a number of jade samples here from a
jeweller with an impeccable reputation (not named for different
reasons). The hardness seems pretty constant so far at what I
estimate to be 6 to 6.5 but the shatter-resistance (toughness) varies
greatly. I will get assays back soon on 53 elements. I am thinking
that the variable shatter-resistance is due to physical crystal
growth and strengthening by inter-twining. But the assays may say
otherwise. It may be that the weaker pieces are so because of the
admixture of other minerals in the ore.
The crystal growth for enhancement issue makes me wonder if the
ultimate test of whether jade or jadeite is the superior gem stone
will be found in GE labs. If “pure” jade mineral and pure jadeite
mineral matter are subjected to optimal conditions of heat and
pressure for enhancement then which produces the “created” gems which
will look more like emerald? If it is a tie by the criterion of
beauty then jade wins over jadeite in that it gets more points in
durability. If GE can mass produce either at the same cost, then it
is a tie in rarity. Which can be enhanced more in hardness? And what
weighting does one give to the criteria?
When it comes to hardness as a durability criterion, I have to go
back to the parameters of chemical composition. I referred earlier
to the Audubon field guide which points to Fe variation. Leaming
refers to Mg and Ca variation and also to the admisxture of other
minerals in jade ore from magnetite to garnet which may enhance or
detract from the final gemmological product depending on what one
calls gem beauty. With all this chemical variation one may well ask
at what stage jade ceases to be jade and that I think is what you are
pointing to when it comes to the OH bonds. BTW if you google on
asbestos there is a reference to asbestos minerals (of which there
are six) being used in early pottery to strengthen the clay,
apparently because of its fibrosity. I suppose that would work,
further to your point above, for a certain temperature range in the
treatment of the pottery. If the pots were used in cooking they
might lose the enhanced strength after heating and becoming
anhydrous.
The usefulness of diamond ranges from diamond grit to larger cut
stones. The ancient Romans had no use and no value for diamond
because they could not cut it or grind it and a diamond field stone
is no more aesthetic than a piece of rough glass. Has anyone heard of
whether the Romans ever figured out if rough diamond might be used to
cut other stones? I do not know if diamond powder is of use. But what
about jade powder, eg in pottery? Jade is jade whether it is a
powder or a 100 ton boulder.
Jade is BC’s official stone although it seems Senator Neufeld et al
recently wanted to change it.
http://www.msacomputer.com/bc/Gemstone/Gemstone.html
I do not wish to be responsible for boring 10,000 Orchidians and
this “thread” is getting lengthy and somewhat specialized so I will
take the liberty of using bcc for a few parties who may be interested
and suggesting we continue it on another list for those who want to
go into it more.
When I talk about jade I mean BC jade which is chemically an
amphibole-class mineral. So far no jadeite, a pyroxene-class mineral
has been found here. I painstakingly extracted one gram of
emerald-green crystals from a matrix after one of my prospecting
trips and I will let Orchid know after assaying if I did find
jadeite. Not likely but then prospectors passed over diamond crystals
on a trail which became a highway in Ontario for over a century
before they did the assay and discovered what they were.
Meanwhile, I have seen white jade and black jade in the jewelry
shops of downtown Vancouver. The two jade carvings I had the temerity
to smash up and send in for assay are a “whitish” jade and a high
grade dark green jade. In the context of the Orchid thread on
California blue jade I have to wonder how it would assay. How far I
go with my present smash-and-assay experiments depends on the assay
results I get back this month. Smashing jade carvings (even though I
buy the cheapest I can for this purpose) is, however, something I do
with reluctance. BTW one jewelry shop told me that their white jade
comes from Whistler, BC. Can anyone confirm that? It is new to me.
Jade dust is a by-product of BC jade mining and carving. Is it of
any use? I refer below to the historical use of asbestos-class
minerals to strengthen pottery because of their fibrosity. That
includes jade dust. I also agree that heating the pottery beyond a
certain range would drive off the OH bonds and have the reverse
effect of weakening the pottery. But my recent experience with “hand
building” of clay pieces tells me that while a room-dried clay
carving may be very nice, it is also very fragile. Jade dust may
strengthen it. And maybe it would even strengthen “bisque-fired”
pieces or super-dried pieces a la Leaming below as long as the
temperature treatment is not excessive. How much heat-treatment is
required to enhance a jade-augmented hand-built clay carving? This
too becomes a sculpting with “enhancing jade”. (I’ll put Leaming’s
“semi-jade” aside for now until we exhaust the jade issue).
The strengthening depends on how well you can intertwine the matrix
of your hand-built sculpting with jade fibres. Since clay particles
are known for their incredibly small size this may work in a kitchen
blender. I would be like having a ball of string around them. I will
let you know.
If the jade mineral fibres are extremely well mixed with a mineral
matrix, that may even bode well for GE labs and their creation of
jade and jadeite. Why not try to use the jade in the magma press to
strengthen the whole matrix? If jade in nature is twined around
various other minerals (which may add colour like blue or black) then
why not jade in a GE lab? Imagination at work in nurturing minerals
in the lab? While pyroxenes may be fibrous I think amphiboles are
more likely to be so. Others may opine otherwise.
Imagine all the enhanced jade mineral mixes one might develop. In
meeting the gemmology/Orchidian criteria of (1) rarity; (2) beauty;
(3) durability, “GE Enhanced Jade” might do very well. It may surpass
any known natural jade or jadeite in hardness, shatter-reistance and
beauty. I think Rod on BC-Free list is still wondering about those
pretty green crystals he once found thousands of feet down in a drill
hole so I should qualify that by saying that nature may in the end
win the jade enhancement contest of nature vs. nurture.
Am I correct that jadeite is not usually fibrous but rather massive
in its growth habit while jade is always fibrous? That being so, the
lab tests may prove jade to be the superior gemmological product by
all criteria over jadeite.
I have to read :Leaming as saying that JADE (not jadeite) was the
stone of the Emperors of China. Maybe they foresaw this outcome of
which is the superior stone thousands of years ago.
It appears that the term “jade” as used in the foregoing refers to
nephrite, the only “jade” known to the Chinese in the centuries
before the 18th. So we are to examine criteria as gem material:
rarity, color, hardness, and durability are the ones that seem to
fit “jade.”
So, is nephrite superior inall criteria? Not at all. The best
jadeite has by far the most attractive color, something no "lab test"
is likely to reveal, and this best color is extremely rare. The very
best nephrite is downright ugly compared to a translucent emerald
green jadeite, which can be truly astonishing. How about durability.
Jadeite is somewhat harder than nephrite, but probably less "tough"
than nephrite. Both are often carved into delicate thin sections
without chipping, so both are quite durable in that respect. As a
ring stone nephrite will lose its polish very quickly, so its lack of
hardness is a fault.
Jadeite is typically found in crystalline aggregates rather than the
fibrous masses seen in nephrite. Guatemalan jadeite often has fairly
large individual crystals, very different from the typical nephrite.
Personally, I find nephrite more pleasant for handling, owing to its
almost waxy feel and the absence of visible texture. Perhaps this
almost mystical quality is what appealed to ancient civilizations, in
addition to its fine qualities in carvings.
It would help to search out and examine many specimens of both
jadeite and nephrite to get a personal baseline of experience rather
than relying on some book that may be too narrowly focused in its
approach.
Have fun!
Dick Davies
It appears that the term "jade" as used in the foregoing refers to nephrite, the only "jade" known to the Chinese in the centuries before the 18th. So we are to examine criteria as gem material: rarity, color, hardness, and durability are the ones that seem to fit "jade."
No. Of course not
So, is nephrite superior in*all* criteria?
No. Of course not
Not at all. The best jadeite has by far the most attractive color, something no "lab test" is likely to reveal, and this best color is extremely rare. The very best nephrite is downright ugly compared to a translucent emerald green jadeite, which can be truly astonishing.
OK, then which is the ugliest piece of jade in the whole wide world?
And how would the best jade stone from a GE press (if that is the
correct word) compare to the best jadeite stone?
BTW, GE managers are considering whether to sell their stock in a
hostile takeover bid. So we have put forward a genuine offer to
purchase one of those presses as long as it is suitable for this kind
of testing. Why not sell GE in bits and pieces?
How about durability.
Jadeite is somewhat harder than nephrite, but probably less "tough" than nephrite. Both are often carved into delicate thin sections without chipping, so both are quite durable in that respect.
As a ring stone nephrite will lose its polish very quickly, so its lack of hardness is a fault.
Interesting point, thank you. I had not heard this before. I wonder
then about using epoxy or other chemicals as surface polish? I may
give it a try here.
Jadeite is typically found in crystalline aggregates rather than the fibrous masses seen in nephrite. Guatemalan jadeite often has fairly large individual crystals, very different from the typical nephrite. Personally, I find nephrite more pleasant for handling, owing to its almost waxy feel and the absence of visible texture. Perhaps this almost mystical quality is what appealed to ancient civilizations, in addition to its fine qualities in carvings. It would help to search out and examine many specimens of both jadeite and nephrite to get a personal baseline of experience rather than relying on some book that may be too narrowly focused in its approach.
Perhaps there is a truncation/moderating problem with these
postings. I explained that we ARE sampling extensively with jade and
running assays and other tests.
I was pleased to receive a Christmas eve gift of assay results from
the lab and a paper on jade formation from fellow prospector Keith
Ludemann. Keith’s paper was by Harlow and Sorensen “Jade: Occurrence
and Metasomatic Origin” from the International Geological Conference,
2000.
The assay results show clearly that the samples I sent in are from a
rock with complex dimensions causing variation more than a
homogeneous mineral. There are about a dozen such dimensions which I
would like to discuss and if I present them one by one, perhaps each
sub-topic will be short enough to be postable to Orchid. The bottom
line is whether those jade variables can be harnessed in GE lab
equipment to make jade by simulating the “metasomatic” processes of
nature (do a wiki search on that word).
As posted earlier, I selected two contrasting samples of carved jade
from a jeweller with as high a reputation as you can get here in
Vancouver region. The mine source is also known. Reluctantly I
smashed the carvings for assay and found significant differences in
the shatter resistance variable which I though might be explained in
part from the assay.
Since BC jade is hydrous calcium-magnesium-iron silicate, if the
jade jewelry is a homogeneous mineral it should show only significant
amounts of Ca, Mg, Fe in the assay. The other 50 elements returned
should be insignificant (silicon and water are not included in the
assay return). Rounding off, here are the % values of those three
elements in the two samples:
…3 1.6.7
…3 1.5.6
Is there a chemist here who can say what the ratios should be from
the jade chemical formula?
Since less than 3% of total weight is Ca, Mg and Fe, a lot of rock
is still to be accounted for ! The conclusion is that this is a
sampling of jade rock, ie a jade ore body. It is typical of the
material used in jade jewelry/carvings. In the shop from which I drew
the samples, more expensive pieces run into many thousands of
dollars.
Let me just put forward one other element in the jade rock. Aluminum
values are in the same ballpark as the Ca, Mg and Fe values. Al in %
is.7 and.6
Those Al values are typical of dozens of other assays I have here,
from polymetallic sulfide rocks to slate family rocks. Since
aluminous feldspar is the most common mineral by far, no doubt that
is part of the reason. If there is interest I can proceed with the
assay results.
In every way, these assays and other tests tell me I am dealing with
a typical rock more than a homogeneous mineral. If we understand
those variables enough it may be possible to simulate the
transformation of elements and their mineral compounds in the lab
and make superior jade. Some day synthetic jade may be mostly
lab-made as industrial diamonds are now made. The paper Keith sent
says the magic numbers on T are in the range of about 100-550 degrees
C and pressure < 2 Kbars.
Is that what GE labs use?
If this thread is too narrow or specific for Orchid, we can take it
to a more suitable list.
One question raised by the assay is far beyond my chemical
capabilities though and I was hoping an Orchid stone chemist could
help. I am puzzled by the low total % of Ca/Mg/Fe even though no
jeweller would dispute that the stones assayed are genuine BC jade.
The comparatively high Al value also is a point for discussion.
How does one convert those % figures to total actinolite-tremolite
using the chemical fomula? My guess would be that total a-t is not
more than 10%. Whatever it is, it immediately presents the variable
of a-t concentration. Is an ore with 20% or 30% higher grade? Is an
ore with higher Al value still jade ore?
More broadly this bears on how one would chemically enhance jade ore
in a GE press. Should Al be added? What about Cr or Ni? Do some
additives act like an “alloy” by increasing stone strength? It sounds
like Rock 9 has seen quite a lot of jade in the field and he may have
an opinion on variation in “wild jades” as contrasted with those in
gem shop windows.
Again - I will not name the BC mining company which is the source of
my samples but they are well lnown and have put forward the question
raised in the two contrasting samples by WWW. Their reputation has
never been questioned that I know of and I have no intention of
questioning it; nor do expect any of my data to call it into
question.
If there is interest I can go into the rest of the 53 elements in
the assay and also my tests on them as a field prospector re their
hardness, SG, reaction to acid, reaction to hammer blows and
scratch-resistance etc.
The jade samples from a Vancouver jewelry shop which I had assayed
prove beyond any doubt that jade is a rock.
Hopefully an Orchid chemist will correct me if I am in error, but
here are my calculations. First I took the standard chemical formula
given for actinolite-tremolite. Then I went to the link for Peridioc
Table at Empirical Formula and Molecular Formula Chemistry Tutorial
to look up Ca, Mg and Fe. and find the relative atomic mass for
each. The ratios of these elements in the actinolite-tremolite
formula were multiplied by their respective ram.
Ca: 2 x 40 = 80; Mg 5 x 24 = 120; Fe 5 x 56 = 280. The sum is 480.
Doing the same for O, H and Si and we find that the ram total of one
mineral molecule is 1090.
Since the sum of the assay values I posted earlier for Ca, Mg and Fe
add up to only about 2.5% that means the actinolite-tremolite in the
samples is less than 6%.
Given that over 90% of these jade carvings was not
actinolite-tremolite, they fit the definition of rock carvings and
not mineral carvings. Jade is a rock.
Also I was asked off-list about how to get these assays done. I have
no vested interest in Acme Assayers in Vancouver but I can recommend
their work highly. Google on Acme. You can mail in one gram samples
of jade or _____ and be sure to specify if you want assayed samples
returned, stored or destroyed.
If Orchid jewellers et al pool their assays they can share the
up-front (fixed) batch fee. Acme will send the assay results to
contributors by email.
I had predicted the finding that jade is a rock. I did not predict
the magnitude. It amazes me that less than 10% of a rock’s
composition by weight can bind the rest of the rock with mineral
fibres/strands/needles so powerfully. What if the % was higher or
lower? What would that do to the value of the stone? What if GE lab
is able to produce 100% pure actinolite-tremolite jade with mineral
fibres intertwined to the maximum? What kind of gem would that be?
Another “jade variable” which is highlighted by these assays is the
role of other minerals in the mix. The values of Cr, Ni, Al, Hg etc.
are significant. What do these elements and their minerals do to
jade durability and beauty? What would “GE super-jade” be like?
Perhaps it will surpass anything we have yet seen in nature.
Since Cr in even tiny amounts is regarded as a jade and jadeite
colorant, perhaps the “emerald green” in the highest value jadeite
gems (which can fetch emerald-like prices) can be surpassed by
superjade.
I have also found stunning green crystal samples in my prospecting
of a jade ore body in the field. I had hypothesized that these were
green garnets (Cr garnets) but the assay is so surprising that I
have to wonder if this is a new mineral. Can anyone explain a Se
value > 10,000 x the Earth Crust Average? With dozens of other Se
assays here nothing comes even close. In any case, one implication
is that superjade colorants in a GE lab could match or surpass
emerald coloration.
Also consider that the Audubon field guide to minerals gives the
same chemical formula for actinolite and tremolite but says that Fe
content may vary. Leaming gives the same formula but says Mg and Ca
may vary. Leaming also refers to variation in the OH bonds.
It is not clear to me what Leaming means by “semi-jade” in his
book.Perhaps what he is getting at is that chemical variation in
jade may cause it to shade off into another kind of rock or mineral.
What would happen in a GE lab if various amphibole family minerals
were mixed with various pyroxene family minerals?
Finally a health note. If you do a lot of this work remember that
the biggest class action law suit is not for tobacco but for
asbestos family minerals which includes actinolite-tremolite. Not
only do they clog the lungs like silica but they are also
carcinogenic.
When GE made their jadeite they first had to make a glass of the
right stoichiometry and then that was heated under a pressure of
several GPa. That is hundreds of times greater pressure than you need
for forming your amphibolites. They also only made pieces about 1mm
thick and these werent homogenous.
Industrial diamonds are made in a different way now to those made a
couple of decades ago, hence the reduction in cost. Also, they have
a purpose, which cannot be said for synthetic amphiboles.
Nephrite jade is only thus because of its colour. Yes, it is a rock
composed mainly of 1 mineral but it is only a loose description based
upon someone’s interest in a green bit of rock of a particular shade
with particular patterns. As has been pointed out, most jade from
chinese workshops isnt jade at all, it is quartz, serpentine, marble
and many others. The common theme is the colour being approximate to
those found in jadeite. Rubies are red, every other corundum gem is
called sapphire. If it is not a gem it is just plain corundum and
worth very little. When corundum is synthesised it is commonly done
in small range of colours. Why? not for gem use, that is still a
relatively small market. It is used for optical devices, in
electronics, as a thermal barrrier, as a window for devices
undergoing a rapid temperature change such as lasers etc. When I
worked in a geological laboratory I used to subcontract make
sapphire windows for heating/freezing stages for microscopes and
substrates for thin layer semiconducting devices and junctions for
laser and optical fibre devices. It was the thermal and optical
properties that made the choice of material. Unless you can find a
similar rationale for synthesising amphiboles then there is no
imperative to do so. Why not just use quartz, serpentine marble etc
if it looks pretty. Most of the value is added by the carving. Look
at agate carvings, they are worth considerably more then the $20 a
ton the raw material is worth at the mine. Does your rock look
pretty? If not give up and look elsewhere as you cannot make a silk
purse out of a sow’s ear.
Nick
As I have said before, jade is a name and nothing else unless you
qualify your statements. You bang on about the bulk chemistry of your
rock but you havent shown us any pictures of nice green workable
material that make a particlar assemblage a rock called jade. You
cannot use your bulk chemical data to extrapolate that this means you
have x% of a particular mineral because you have no structural or
crystallograhic data to support your assertions. You will get a
similar chemistry from clay. The only real conclusion you can reach
from your analysis is that you do not have jade but even this is
flawed How can you say what 90% of the carvings were when you arent
applying the correct analytical method to determine mineralogy. You
need to stop hypothesising and take a few steps backwards. Does your
rock look like jade? ie: is it green, have a greasy lustre, the
correct hardness etc. If it doesnt fulfil these criteria then it
isnt jade, it is an actinlite tremolite series amphibolite similar to
most of Greenland, a large chunk of Canada and most of the Alps in
europe. It is the recognised gem properties that decide if people
want to call it jade. All the other questions on the bulk chemistry
are made inconsequential for this determination. The short answer is
they are present in other minerals and can be detected because you
have looked for them. You ask about levels of Hg and Se? thery are
found together as Clausthalite if I remember correctly, a mineral
associated with lead and gold in Brazil and with sulphides in the
metamorphics of the Alps. I recommend you read something like “A
Handbook of Rock Forming Minerals” by Deer, Howie and Zussman. It
cantains a lot of analyses of the common mineral types and arranges
them into groups based upon their structure with optical and physical
properties and characteristics. Cr is NOT a colourant in jade or
jadeite, it is the oxidation state of the iron that determines
whether you get blue or green amphiboles. Ditto for sapphire. The Cr
so cannot be compared. as a chromophore in emerald occupies a
different part of the crystal lattice. You can get lovely chrome
diopsides which are a peridot green, these occur as huge crystals in
the Yatkusk region of Siberia but I wouldnt call them jade. Perhaps
the Chinese will if it suits them to.
The variations of Ca, Mg Fe and others is because the minerals are
a solid solution series and people refer to them by the end member
names. The same applies to for example, feldspars where you get
Na-Ca feldspars and Na-K feldspars but never K-Ca because of the
lattice parameters. You do get K-Ba substitution though. Paracelsian
is used as a glaze additive.
You also keep refering to GE labs synthesis of jadeite. Yes, they
tried and wrote a paper on it and their work was improved by others.
It will never be commercially viable because there isnt a market for
very expensive opaque glass. They are never going to synthesise
amphiboles because there is no point in them doing so. All these
what ifs are questions that can be easily answered without wasting
time and money in a commercial research lab. Amphiboles and pyroxenes
heated together make pyroxenes or amphiboles, depending upon the P
and T. You can make garnets or even mud out of them but again, unless
you are trying to reinvent the wheel you wouldnt bother because all
of this was done in the 1970’s by geologists in various parts of the
world such as Rick Sibson in New Zealand and Ernie Rutter in
Manchester.
Finally as there is no such single entity called jade the term
semi-jade is even more meaningless. Jade is just a word that gives
people a common understanding, perhaps we should use the vaguer
Chinese word, Wu.
So to recap: if it is not a pretty, dense, green almost
monomineralic rock it is not jade regardless of chemistry. If it IS
all of those then it is jade, regardless of chemistry.
Nick Royall
Nephrite jade is only thus because of its colour.
I would define it as a rock containing enough actinolite-tremolite
mineral in a mineral growth pattern/habit to enhance the rock and make
it of interest as potential dimension stone/cut stone material. The
actinote-tremolite content can in theory range from miniscule to 100%
and the latter would make it a pure mineral.
Thus my earlier claim that jade is both a rock and a mineral.
Leaming does not define semi-jade except to say it is not as hard as
jade. Maybe he is talking about bowenite. Also there are serpentine
rocks which look like jade. Anyway given that this “subjade” can be
enhanced, why not “superjade”? Indeed Leaming says that jade itself
can be enhanced 50% in hardness. Is that “superjade”?
Yes, it is a rock composed mainly of 1 mineral
What mineral would you say that is? The assays I posted prove that
the actinolite-tremolite content is
... When I worked in a geological laboratory I used to subcontract make sapphire windows for heating/freezing stages for microscopes and substrates for thin layer semiconducting devices and junctions for laser and optical fibre devices. It was the thermal and optical properties that made the choice of material. Unless you can find a similar rationale for synthesising amphiboles then there is no imperative to do so....
The rationale might be called “stone enhancement”… not only for
jade but other stones too. I just had a Duncan 1029 kiln hauled into
my backyard and I note that it fires up to 2345 F which is beyond the
range of most magmas. Isn’t that what pottery mineral glazes are -
magmas? Then what if I melt some amphibole mixes from the field in
this kiln? Or why not other stoney mixes for enhancement?
Leaming would agree with you that in some quarters of China, “jade”
is any pretty and carvable stone. But let’s stick with amphibole jade
for present discussion. I am prospecting in rock groups and
formations now which GSC Open File 3511 (1998) describes as “foliated
sedimentary and volcanic rock”. I am amazed by the diversity of rocks
at all stages of metamorphosis but amphiboles abound. Do I want to
make jade? Yes and no. I have a 30 lb chalcedony river stone which is
mottled green, mauve and white and I will pit it against any jade
river stone for aesthetics. Cutting jade is a snap compared to that
stone. Wish I could find more.
I may be able to make something prettier and better than most jade
in the shops by completing the job in my kiln turned smelter where
mother nature left off. She’s a great old bird but she’s not perfect.
I note from Fire clay - Wikipedia that some potters
bundle pots etc in “a heavy wrapping of metal foil”. Does anyone know
what this heat-resistant metal is? Why not melt all kinds of
mountain-source fine loose sediments in it? Or pulverize stones and
melt them.
Next stage - How to (s)melt stones and pressurize them as well
without blowing up the town like Rambo (I prospect around the
original Rambo filming site in the Fraser Valley). There are
engineering firms which specialize, eg PEI and TPENG. Also I am
trying to get on an online engineering forum to discuss this.
http://www.eng-tips.com/faqs.cfm?fid=1339
As you noted too, the T/P of gemmologically-interesting stones in
nature is variable, eg jade takes
Throw out the color green, because good nephrite jade does not have
to be green, yes most jade is green, but I have other colors,
As you posted to Orchid, “good jade does not have to be green”. I
have examined hundreds of pieces in jewelry shops and more in the
field and I agree. What I wonder now is what colourants I should use
in making “jade glass” in a kiln as below. What would you suggest?
Given that jade is usually a rock with >90% not being
actinolite-tremolite, the possibilities for that 90% are huge. The
white jade reportedly from Whistler, BC which I found in one shop -
Is that from a high content of aluminous albite? Is the black jade
which I have seen in a shop and also in the field just
"horneblendite" with a few % actinolite-tremolite?
I have six jade assays here of greenish jades. All contain high Cr
which causes green colouring does it not? And doesn’t Mg also make
rocks green?
When I get this kiln going in the spring, it will do up to 2345 F.
That will melt jade easily. So why make jade bricks/tiles? Leaming
tells the story of the rich woman who wanted to walk on her jewelry
and not wear it so she had her entire house tiled with jade. If jaded
is defined as below, why not make jade tiles and colour them any
colour you want? Yesterday took a complex, multi-coloured sample from
the field which contains some of the favoured translucent soft
apple-green colour and I carefully chipped that out for assay. Assays
can be used to get clues about colourants.