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#151

Lefty
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Joined: 01 May 2014
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15 April 2018 07:22 am

Diamonds almost all occur in kimberlite pipes prior to erosion. These are quite rare and come from very great depth, and are mostly only emplaced into very old rocks. Sapphires tend to be associated with alkali basalts in many parts of the world and these are widespread (the exceptions are in other very rare rock associations). They come from lesser depth and don't care what age rocks they are emplaced in. So far more sources for sapphires than diamonds (the same follows for the alluvial stones as they depend on the hard-rock sources). There is method in it all Lefty....

What's your take on the reason (assuming the figures I've read are remotely accurate) that global sapphire production does not significantly outstrip global diamond diamond production? Certainly diamonds bring a lot more $$$ but sapphires are also up there with the ranks of "true" precious stones and are worth mining even in high-cost places like Australia. Is it that diamond mining is conducted mainly by "the big boys using lots of big toys" and high-tech equipment and a highly advanced global marketing system versus the more modest approach to sapphire mining?

That was the point behind my question. I don't disagree that there are a lot more potential sources for sapphires - in addition to the places you listed, I'm aware of their existence in several other places in eastern QLD as well - but....

we see them all the time in central Victoria but too small to cut in the main

....seems to be a recurring theme.

Before he was into gemstones, my old man was a mad keen gold prospector. If I listed all the places he found gold traces it would give the impression that gold is very common. However, it boils down to whether or not an area has it in sufficient quantity to be worth going after - that context is crucial.

In that context, corundum as a mineral may be more common and widespread than diamond but gem quality corundum - which includes not only colour and transparency of the material but size as well - does not seem particularly common in the main.

#152

Lefty
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Joined: 01 May 2014
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15 April 2018 07:44 am

Here is a 2003 observation by a sapphire miner at Lava Plains, that is much what I would expect:

http://www.australiansapphire.com/sapph … theory.htm

"We tried some mining techniques which would have had conventional miners questioning our sanity - but they worked, and we found sapphire! We left the alluvial systems and started mining the huge deposits of volcanic ash which blanket the area - and we found excellent sapphire.
We stripped off layers of lava flow rock to expose further layers of volcanic ash below - and again we found more sapphire".

Yep, that's a good read that article. I've spoken to quite a few diggers out on the field who agree that the arguments Jim advances there make a lot of sense in their own experience.

Jim used to own a local earthmoving business in my home town and moved to the field to start sapphire mining around the same time we were working our claims at Russian gully.

I'd agree with him that many of the quartzite "billy boulders" do have a surface appearance that looks more sort of heat-glazed rather than stream-worn.

I'm not sure why he didn't continue with the lease at Lava Plains - I have a feeling he didn't actually make all that much out of it. The stones tend to be fairly small in general for one, so I've been told at least. Could also be the area's isolation, lack of reliable washing water in the dry season, the torrential rain of the FNQLD wet season making mining impossible for a good part of the year - not too sure of the reasons?

There is a bit of a caveat to his statement "the size and quality of the sapphire tended to diminish the further we went from the basalt plugs". There seems to be a zone immediately surrounding the plugs (on the Anakie field) where the stones appear almost absent - this seems to be common knowledge among the miners on the field and I think I've read it in a geological publication as well. They are generally not found either embedded in the basalt plugs nor immediately around the plugs but start to appear further out.

#153

Mungoman
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Joined: 26 March 2014
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15 April 2018 09:41 am

This all makes sense, how sapphires are found in the ash, and not found around the plug.

I was told that sapphires are formed in vents of the volcano, rather than in the magma, or lava - and sapphires are blown all over the countryside if and when a volcanoe erupts/blows up.

I don't know how true that theory is but the above seems to confirm it in my mind.

#154

goldierocks
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15 April 2018 06:50 pm

Lefty wrote:

Diamonds almost all occur in kimberlite pipes prior to erosion. These are quite rare and come from very great depth, and are mostly only emplaced into very old rocks. Sapphires tend to be associated with alkali basalts in many parts of the world and these are widespread (the exceptions are in other very rare rock associations). They come from lesser depth and don't care what age rocks they are emplaced in. So far more sources for sapphires than diamonds (the same follows for the alluvial stones as they depend on the hard-rock sources). There is method in it all Lefty....

What's your take on the reason (assuming the figures I've read are remotely accurate) that global sapphire production does not significantly outstrip global diamond diamond production? Certainly diamonds bring a lot more $$$ but sapphires are also up there with the ranks of "true" precious stones and are worth mining even in high-cost places like Australia. Is it that diamond mining is conducted mainly by "the big boys using lots of big toys" and high-tech equipment and a highly advanced global marketing system versus the more modest approach to sapphire mining?

That was the point behind my question. I don't disagree that there are a lot more potential sources for sapphires - in addition to the places you listed, I'm aware of their existence in several other places in eastern QLD as well - but....

we see them all the time in central Victoria but too small to cut in the main

....seems to be a recurring theme.

Before he was into gemstones, my old man was a mad keen gold prospector. If I listed all the places he found gold traces it would give the impression that gold is very common. However, it boils down to whether or not an area has it in sufficient quantity to be worth going after - that context is crucial.

In that context, corundum as a mineral may be more common and widespread than diamond but gem quality corundum - which includes not only colour and transparency of the material but size as well - does not seem particularly common in the main.

Two different things - quality and size. I would say that gem quality corundum is very common, far more common than diamonds, but that it is rarely large enough to cut. Also, diamonds are mostly industrial, not gem. The figures you quote seem about a thousand times too high. Total world diamond production in 2017 was only 134 million carats which is 28 tonnes, mostly industrial (I don't know the proportion of this that would be gem, but at Argyle it is 5% and some other places 20%). So perhaps 3 tonnes of gem diamonds per year for the world, compared with 36 tonnes for corundum gems (mostly sapphire).

Diamonds are much harder than corundum, so this may also be a reason for larger diamond production. Corundum may be 9 and diamond 10 on Moh's hardness scale, but the scale is not linear - diamond is much, much harder (so there would be less demand for industrial sapphires). Also much of the world's sapphire production is alluvial and not amenable to bulk mining (and kimberlite is a soft rock, easy to crush).

You said "I can't speak to how often they are found attached to host rock in other places but I've never seen it or even met anyone who has ever heard of it occurring on the Anakie field, barring the sole example of the one embedded in the Mount Leura plug...................it's clearly a rare phenomenon in my area at least". I was not listing "potential places for sapphire" - my list was of places where sapphire is actually found (and in some cases mined) in rock in eastern Australia - quite a lot.

When I was in South Africa years ago, a jeweller friend said that he and his mates would barely touch coloured stones such as sapphires any more - too many good synthetics, and people buy them as a store of wealth (so high demand) and there is a well established system for valuing them (I don't know if that is a factor). Synthetic diamonds are now made but are only 2-3% of the gem market. If you buy for investment, you don't want to have disputes over what they are worth when you want to sell. Diamond valuation and pricing is tightly controlled, with 85% of the world's diamonds traded in Antwerp/London.

Last edited by goldierocks (15 April 2018 07:34 pm)


Robert Benchley...
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#155

goldierocks
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15 April 2018 07:46 pm

Another issue that affects what is mined is the value per stone - although there are exceptional prices for some individual stones, the average price of a 2 ct diamond would by around 8 times that of a blue sapphire of the same size.


Robert Benchley...
I have kleptomania, but when it gets bad, I take something for it.

#156

deadpan
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Joined: 27 March 2018
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16 April 2018 03:22 am

goldierocks wrote:

Another issue that affects what is mined is the value per stone - although there are exceptional prices for some individual stones, the average price of a 2 ct diamond would by around 8 times that of a blue sapphire of the same size.

That issue can only be used if they are finding the same ct./quantity of each stone to be fair.

#157

Heatho
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16 April 2018 08:26 am

goldierocks wrote:

Another issue that affects what is mined is the value per stone - although there are exceptional prices for some individual stones, the average price of a 2 ct diamond would by around 8 times that of a blue sapphire of the same size.

Errr that's not quite true if you compare these two stones.....

https://www.thenaturalsapphirecompany.c … re-b6272-/

https://www.diamondimports.com.au/Round … C1271.html

Emeralds and rubies can be way more expensive than diamonds, anyway most gemstone values are subjective, they are only worth what someone will pay.


Minelab GPX 5000, SDC2300, CTX3030, Equinox 800, patience, lot's of patience.

#158

Lefty
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16 April 2018 08:48 am

most gemstone values are subjective, they are only worth what someone will pay.

That's the nub of it right there. My fathers collection contains quite a few sapphires that have been formally appraised by a professional valuer and have the valuation certificates. The valuer has valued some of them at prices that I feel they would have some difficulty selling at, except perhaps to a really serious collector.

The valuer is certainly a highly qualified professional - but they are not the buying public.

If John and Jane Public don't agree with the price then good luck in selling it for that much just because you have a piece of paper that says it's worth that.

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#159

goldierocks
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16 April 2018 11:49 am

Heatho wrote:
goldierocks wrote:

Another issue that affects what is mined is the value per stone - although there are exceptional prices for some individual stones, the average price of a 2 ct diamond would by around 8 times that of a blue sapphire of the same size.

Errr that's not quite true if you compare these two stones.....

https://www.thenaturalsapphirecompany.c … re-b6272-/

https://www.diamondimports.com.au/Round … C1271.html

Emeralds and rubies can be way more expensive than diamonds, anyway most gemstone values are subjective, they are only worth what someone will pay.

I didn't compare two individual stones, I compared the mean price of 2 carat stones overall which is what would matter to larger companies. As I said, there will always be individual exceptions, but the mean prices overall are vastly different (for gem quality).

And the point I was making with diamonds is that prices are not subjective at all but tightly regulated by specific criteria. When I was in Joburg you could take a stone into a dealer and be quoted a very similar price to what you would be quoted if you then took it to another dealer. That is what makes diamonds attractive (more attractive than sapphires) as a source of wealth, like gold. Although one cannot control currency fluctuations (like gold) or supply versus demand issues (unlike gold but fairly limited by collusion between the limited number of big suppliers), you know that you will get the going rate when you sell, unlike the more speculative variation of other gems. And yes, rubies and emeralds are more pricey - their production is much lower (rubies around 10 tonnes per annum from memory).1523839840_diamond_prices.jpg

I mention gold because it also has its own controls to a degree and does not behave like a normal commodity. Most people think its price relates to supply and demand (eg mine production) and also speculate on instability and variations in the oil price (with which it sometimes shows some correlation). Demand has exceeded supply by at least 25-33% for as long as I have been closely following it (e.g. 1000 tonnes per annum), and it remains stable by input from central bank, jewellery etc sales, and despite not being an official currency standard it still has some de facto standard value. So huge fluctuations are unlikely except under extreme conditions. I prefer it to diamonds for long-term value (although who knows with measured diamond reserves dropping dramatically), I only buy other gems (rarely, and in the rough, for economic reasons) because I love beautiful stones, and I would not buy e-currency in a fit (although I wish I had). Unless our emigration policies change dramatically property should be good until past 2030, but I am wary right now. And to a large degree it is now irrelevant as I am semi-retired and can't afford to speculate, nor need long-term stores of value.

Last edited by goldierocks (16 April 2018 12:30 pm)


Robert Benchley...
I have kleptomania, but when it gets bad, I take something for it.

#160

goldierocks
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16 April 2018 11:59 am

deadpan wrote:
goldierocks wrote:

Another issue that affects what is mined is the value per stone - although there are exceptional prices for some individual stones, the average price of a 2 ct diamond would by around 8 times that of a blue sapphire of the same size.

That issue can only be used if they are finding the same ct./quantity of each stone to be fair.

I'm working on overall bulk prices - which is how larger companies judge the economics (especially with diamonds). The other stones are a real headache - I once investigated trying to get cooperation by miners on opal sales to limit big swings in price (a day-dream - not bloody likely - as difficult as organising systematic native title negotiations I found). The miners commonly get ripped off, although some might do well with a superb stone that they were willing to sell overseas with much effort rather than to a Korean buyer on the fields with a briefcase chained to his wrist. My comparison is average prices of 2 ct cut stones.


Robert Benchley...
I have kleptomania, but when it gets bad, I take something for it.

#161

goldierocks
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Posts: 1,073
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16 April 2018 12:07 pm

Lefty wrote:

most gemstone values are subjective, they are only worth what someone will pay.

That's the nub of it right there. My fathers collection contains quite a few sapphires that have been formally appraised by a professional valuer and have the valuation certificates. The valuer has valued some of them at prices that I feel they would have some difficulty selling at, except perhaps to a really serious collector.

The valuer is certainly a highly qualified professional - but they are not the buying public.

If John and Jane Public don't agree with the price then good luck in selling it for that much just because you have a piece of paper that says it's worth that.

True for other than diamonds to varying degrees. By the way, Argyle don't sell their champagne diamonds through the diamond exchange - their diamonds were given a much lower valuation by valuers (I suspect still are) so they decided to sell direct to the public and launched a big and successful advertising campaign to convince the public of their value. I think many a Joe and Mary of the public gets a shock when they try to sell their precious stones.....

Valuers here are less experienced in the main and mostly value for insurance purposes (an exaggerated price) - quite unlike the diamond valuers that I was talking about. The certificates mean very little.


Robert Benchley...
I have kleptomania, but when it gets bad, I take something for it.

#162

Lefty
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16 April 2018 02:10 pm

A bit more info here on the possible origins of the "sapphires are rarer than diamonds" meme. Looks to be a GIA article

It is safe to conclude that up to and through the
1970s, the market for faceted blue sapphire and ruby was small relative to the quantities in the jewelry
industry today, simply because supplies were
limited primarily to the low percentage of facetable
goods (typically less than 5%) that came from the
mines in salable colors. The introduction of effective
heat-treatment techniques to improve the color
and clarity of previously unsalable material, such as
geuda sapphire from Sri Lanka and dark, “silky”
blue stones from Australia, greatly increased the
quantities of sapphire available to the market, particularly
in the lower-priced commercial qualities.
A similar situation occurred with ruby in the midto-late
1980s after the Mong Hsu deposit was discovered
(Emmett, 2007). And not only did treatments
greatly increase the proportion of facet-grade
material available, but they also allowed development
of deposits where there was little or no naturally
occurring gem-quality material

Having chased sapphires for around the past 35 years or so, this makes sense to me. They are hard enough to find in the first place and when you do, a great deal of them are simply not of gem quality. However, significant numbers of those that are useless as gems in their natural, untreated state can become clear, attractive stones once heat-treated.

Heat treatment has always been available for as long as I have been involved in them as I recall. However, before the process became perfected and widespread, I can easily imagine just how low the rate of recovery for facetable material would have been overall.

So as they come naturally from the ground, a stone that is too small to cut does not a gem quality stone make, except perhaps in a technical sense - and close examination of such tiny stones under powerful magnification might well show that just because you can see through them at a glance it doesn't necessarily mean they are gem quality. By the same definition we might be able to say that gem-quality zircons are as common as sand because there are beaches made of them, even if they are pin head sized and could never be cut. Likewise, a sapphire that is thick and murky with silk (a common occurrence with them despite their overall scarcity) cannot be any more regarded as gem quality than can an industrial grade diamond. Not until it is heated - but it did not naturally come from the ground that way.

Looks a bit difficult to me to make a definitive assertion that one stone is dramatically rarer than the other in naturally-occurring, untreated gem grade material, especially given that sapphire production is not as thoroughly reported and controlled as diamond production. After all the years I've spent chasing them I don;t think I would describe tiny, transparent sapphires below facetable size as "very common" - otherwise I would have drums full of them simply from hand-mining.

This has been an interesting discussion and I'm glad it was held. But I can see it's heading toward unproductive territory so I will now withdraw from it.

#163

goldierocks
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16 April 2018 05:06 pm

I agree. I would not say tiny ones were rare here (often a few in a gold pan) but most streams cannot be mined or prospected. Yes, I enjoyed the discussion and learnt some things.


Robert Benchley...
I have kleptomania, but when it gets bad, I take something for it.

#164

Dappa
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From: Beechworth, VIC
Joined: 27 March 2018
Posts: 33
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16 April 2018 11:20 pm

Hear in north east Vic I've seen people find sapphires,diamonds,ruby's Sapphires are not that rare here i have seen a few diamonds and one or two ruby's


Adapt Improvise Overcome

#165

22shells
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Joined: 11 September 2014
Posts: 187
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22 April 2018 12:39 am

Anyone know what this is? Big chunk of quartz with something on it that I found a few weeks ago, could it be jasper? Fairly smooth with interesting cleavage.
1524317941_p4211018.jpg

#166

goldierocks
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22 April 2018 01:51 am

Jasper or chert would probably be reasonable terms. Incidentally, we don't call those surfaces cleavage - cleavage consists of parallel, planar surfaces that have a constant angular relationship to each other if in different directions, We call what is in your specimen fracture, and that particular type of fracture we call conchoidal (I think it comes from conch - like the inside of a shell). It is typical of many types of glass when they break.
Cleavage is more like this:
https://www.bing.com/images/search?q=mi … &FORM=IGRE


Robert Benchley...
I have kleptomania, but when it gets bad, I take something for it.

#167

22shells
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Joined: 11 September 2014
Posts: 187
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22 April 2018 07:14 am

Thanks goldierocks thumbsup for some reason I thought cleavage and fracture were the same thing, I guess because they are both to do with how it breaks. But you're right, they are different.

#168

LoneWolf
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From: Gold Coast, QLD
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22 April 2018 04:45 pm

Mmmm much prefer Cleavage any day...

LW...


Growing Old is Inevitable.... Growing Up is Optional.... Prospectors United Will Never Be Defeated

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#169

Manpa
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From: Sheidow Park, SA
Joined: 06 January 2018
Posts: 1,207
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22 April 2018 06:05 pm

LoneWolf wrote:

Mmmm much prefer Cleavage any day...

LW...

That made me have a titter, I mean it pays to be abreast of these things or your made to look like a boob. big_smile big_smile big_smile


One of these days Ma!

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#170

Mickomarlin
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Joined: 23 July 2017
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27 April 2018 02:49 am

1524757581_20180427_014147.jpg
Found this on a recent trip to victoria.
Any idea on what it could be

1524757768_20180427_014115.jpg

3 users like this post: roddosnow, 22shells, aussiefarmer

#171

22shells
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Joined: 11 September 2014
Posts: 187
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03 May 2018 01:52 pm

I don't really know Mickomarlin, looks like a big chunk of quartz to me, see what the others say. Nice stone!
Here's a stone with interesting patterns in it that I found where I was getting red/green common opal. So it could be opal of some sort, or maybe something else? Almost looks a bit like those patterns you get in agate?
1525315914_p5021019.jpg

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#172

22shells
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Joined: 11 September 2014
Posts: 187
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03 May 2018 10:27 pm

Another one- little 6 sided hexagonal prisms, many are broken fragments. Seem to be abundant in this particular area. Been calling them garnets but garnets aren't that shape. Maybe rutile? Or corundum?
1525346846_p5031020.jpg

1 user likes this post: aussiefarmer

#173

Heatho
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From: Sydney, NSW
Joined: 29 April 2013
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04 May 2018 10:05 am

Looks more like garnet to me than corundum. There looks to be a clear one just above the centre of the stones.


Minelab GPX 5000, SDC2300, CTX3030, Equinox 800, patience, lot's of patience.

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#174

22shells
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04 May 2018 06:04 pm

Thanks Heatho thumbsup that's what I thought too... but I don't think you can get garnets in that hexagonal prism crystal shape? They're meant to be more like a dodecahedron type shape. That clear one stood out to me too, might be some good ones if I keep looking. Got a bit of dirt to go through that should have more of them in it.

#175

Heatho
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From: Sydney, NSW
Joined: 29 April 2013
Posts: 12,851
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04 May 2018 06:14 pm

I do see what you mean but I still think they are garnet, will be interested to see what you get. Anyway I could be wrong, hopefully Goldierocks has a look at the pic for you. thumbsup


Minelab GPX 5000, SDC2300, CTX3030, Equinox 800, patience, lot's of patience.


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