❓Your Mineral Identification Questions answered here

[Heatho]

In the flesh without the led light it looked a bit like something you might see in some of these examples.

https://picclick.com/278-Carats-WHITE-SILVER-Natural-Uncut-Raw-ROUGH-DIAMONDS-252379670956.html

Anyway, it most likely wasn't a diamond but looked similar to some of this stuff.

 

[Gemsation]

Red garnet , red zircon or ruby ? :/

 

[Lefty]

Zircons and sapphires mostly by the looks.

Nothing wrong with zircon - might only be worth a fraction of the price of Ruby but they are a very fine stone in their own right.

 

[user 4386]

No, was certainly not mica, was a very hard stone and bounced when dropped on concrete. Anyway I guess we'll never know what it was unless I find it again. Not something I'm losing sleep over though. :Y:

I was referring to flakes inside it - but the photo is not really adequate to tell if it is homogeneous

 

[Lefty]

I doubt that sapphires are rarer - we see them all the time in central Victoria but too small to cut in the main. I've never panned a diamond anywhere. However they are not all that rare in pipes, and De Beers would buy up competitors and close the mines, to control the flow onto the market. The best gem diamonds were on beaches in Namibia though - they had been carried hundreds of km down the Orange River to the sea and flawed diamonds broke up in the process, leaving mostly gems (gems are outnumbered by industrial diamonds in the pipes, although the giant gems are mostly from pipes).

It's an interesting question.

Global diamond production seems to outweigh global sapphire production - approx 30 000 tonnes for diamonds per annum versus around 26 000 tonnes per annum for sapphires.

But I have no idea how accurate these figures are. And I'm not sure of context - how much of either represents gem grade versus industrial grade etc. Certainly, a high percentage of sapphires recovered from mining are not gem quality and will never make it to the jewellers display window. Same for diamonds I expect.

Plus, diamond mining is highly mechanised and controlled by big cartels while sapphire mining is smaller scale and fragmentary. There could be more sapphires but they are mined by less efficient means so less end up on the market perhaps?

As you say, diamonds are not all that rare in kimberlite/lamproite pipes which I suppose you could call diamond "ore". I have never seen a sapphire pipe - they are scattered widely among trillions of tonnes of material. Examples of sapphires in host rock are pretty rare in Australia as far as I know at least. A member of this forum found one in a fist-sized piece of basalt in the New England area and apparently a geologist found one embedded in basalt near the summit of Mount Leura near the Anakie gemfields but those are the only examples I know of in this country. Though I have heard of a place in the US where very fine sapphires were recovered from host rock but were difficult and expensive to extract.

Whether it's correct or incorrect, there would have to be a reason that such a meme become widespread. Perhaps it's that sapphires are more common in the Earth's crust but that they are typically very thinly dispersed and not worth going after except in a handful of places where they occur in higher concentrations of larger and better stones?

 

[Heatho]

I doubt that sapphires are rarer - we see them all the time in central Victoria but too small to cut in the main. I've never panned a diamond anywhere. However they are not all that rare in pipes, and De Beers would buy up competitors and close the mines, to control the flow onto the market. The best gem diamonds were on beaches in Namibia though - they had been carried hundreds of km down the Orange River to the sea and flawed diamonds broke up in the process, leaving mostly gems (gems are outnumbered by industrial diamonds in the pipes, although the giant gems are mostly from pipes).

It's an interesting question.

Global diamond production seems to outweigh global sapphire production - approx 30 000 tonnes for diamonds per annum versus around 26 000 tonnes per annum for sapphires.

But I have no idea how accurate these figures are. And I'm not sure of context - how much of either represents gem grade versus industrial grade etc. Certainly, a high percentage of sapphires recovered from mining are not gem quality and will never make it to the jewellers display window. Same for diamonds I expect.

Plus, diamond mining is highly mechanised and controlled by big cartels while sapphire mining is smaller scale and fragmentary. There could be more sapphires but they are mined by less efficient means so less end up on the market perhaps?

As you say, diamonds are not all that rare in kimberlite/lamproite pipes which I suppose you could call diamond "ore". I have never seen a sapphire pipe - they are scattered widely among trillions of tonnes of material. Examples of sapphires in host rock are pretty rare in Australia as far as I know at least. A member of this forum found one in a fist-sized piece of basalt in the New England area and apparently a geologist found one embedded in basalt near the summit of Mount Leura near the Anakie gemfields but those are the only examples I know of in this country. Though I have heard of a place in the US where very fine sapphires were recovered from host rock but were difficult and expensive to extract.

Whether it's correct or incorrect, there would have to be a reason that such a meme become widespread. Perhaps it's that sapphires are more common in the Earth's crust but that they are typically very thinly dispersed and not worth going after except in a handful of places where they occur in higher concentrations of larger and better stones?

Was Kingsolomon who found the sapphire in the rock, I was there when he found it too, we were at Black Springs.

I don't know if it's the host rock where the stone formed or whether the rock attached itself somehow but it's a nice find. I thought the rock is ilmenite but not so sure now. Though I'm sure Goldierocks would have a better idea than me. In the first pic there is also a smaller sapphire below the larger one. The whole specimen rock and all is about thumb size, maybe a touch larger.

If it's ilmenite it makes me wonder if the titanium iron oxide is where the stones derive their colour from??

 

[user 4386]

I doubt that sapphires are rarer - we see them all the time in central Victoria but too small to cut in the main. I've never panned a diamond anywhere. However they are not all that rare in pipes, and De Beers would buy up competitors and close the mines, to control the flow onto the market. The best gem diamonds were on beaches in Namibia though - they had been carried hundreds of km down the Orange River to the sea and flawed diamonds broke up in the process, leaving mostly gems (gems are outnumbered by industrial diamonds in the pipes, although the giant gems are mostly from pipes).

It's an interesting question.

Global diamond production seems to outweigh global sapphire production - approx 30 000 tonnes for diamonds per annum versus around 26 000 tonnes per annum for sapphires.

But I have no idea how accurate these figures are. And I'm not sure of context - how much of either represents gem grade versus industrial grade etc. Certainly, a high percentage of sapphires recovered from mining are not gem quality and will never make it to the jewellers display window. Same for diamonds I expect.

Plus, diamond mining is highly mechanised and controlled by big cartels while sapphire mining is smaller scale and fragmentary. There could be more sapphires but they are mined by less efficient means so less end up on the market perhaps?

As you say, diamonds are not all that rare in kimberlite/lamproite pipes which I suppose you could call diamond "ore". I have never seen a sapphire pipe - they are scattered widely among trillions of tonnes of material. Examples of sapphires in host rock are pretty rare in Australia as far as I know at least. A member of this forum found one in a fist-sized piece of basalt in the New England area and apparently a geologist found one embedded in basalt near the summit of Mount Leura near the Anakie gemfields but those are the only examples I know of in this country. Though I have heard of a place in the US where very fine sapphires were recovered from host rock but were difficult and expensive to extract.

Whether it's correct or incorrect, there would have to be a reason that such a meme become widespread. Perhaps it's that sapphires are more common in the Earth's crust but that they are typically very thinly dispersed and not worth going after except in a handful of places where they occur in higher concentrations of larger and better stones?

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....

 

[user 4386]

Sapphires do occur in hard rock in eastern Australia, found in basalt fragments at Frazers Creek and Waterloo near Inverell, in basalt xenoliths of Mt Leura (Hoy Province), in basaltic diatremes of the Green Hills neck, Blue Mountains and elsewhere in the Sydney Basin, in basalt at Duncan's Ck (Nundle) and in basaltic bombs at Camperdown (VIC). Also in basalt-derived soil (not alluvial deposits) in the Argyle, Inverell and Chudleigh, McLean, Atherton and McBride provinces in north Queensland.

Volcaniclastic rocks emplaced during volcanism are often not recognised as such, especially when weathered, and are an economic source (can be rich as at Braemar). Mined in New England in the Elsmore, Kings Plains and Reddestone Creek areas. The shape of the sapphires is highly irregular, with little sign of abrasion or rounding.

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

http://www.australiansapphire.com/sapphire_formation_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".

 

[Chiron52]

I just read the observation in http://www.australiansapphire.com/sapph theory.htm
Thanks for that, it is a very interesting read goldierocks.
Gives me something to think about.

 

[Lefty]

I doubt that sapphires are rarer - we see them all the time in central Victoria but too small to cut in the main. I've never panned a diamond anywhere. However they are not all that rare in pipes, and De Beers would buy up competitors and close the mines, to control the flow onto the market. The best gem diamonds were on beaches in Namibia though - they had been carried hundreds of km down the Orange River to the sea and flawed diamonds broke up in the process, leaving mostly gems (gems are outnumbered by industrial diamonds in the pipes, although the giant gems are mostly from pipes).

It's an interesting question.

Global diamond production seems to outweigh global sapphire production - approx 30 000 tonnes for diamonds per annum versus around 26 000 tonnes per annum for sapphires.

But I have no idea how accurate these figures are. And I'm not sure of context - how much of either represents gem grade versus industrial grade etc. Certainly, a high percentage of sapphires recovered from mining are not gem quality and will never make it to the jewellers display window. Same for diamonds I expect.

Plus, diamond mining is highly mechanised and controlled by big cartels while sapphire mining is smaller scale and fragmentary. There could be more sapphires but they are mined by less efficient means so less end up on the market perhaps?

As you say, diamonds are not all that rare in kimberlite/lamproite pipes which I suppose you could call diamond "ore". I have never seen a sapphire pipe - they are scattered widely among trillions of tonnes of material. Examples of sapphires in host rock are pretty rare in Australia as far as I know at least. A member of this forum found one in a fist-sized piece of basalt in the New England area and apparently a geologist found one embedded in basalt near the summit of Mount Leura near the Anakie gemfields but those are the only examples I know of in this country. Though I have heard of a place in the US where very fine sapphires were recovered from host rock but were difficult and expensive to extract.

Whether it's correct or incorrect, there would have to be a reason that such a meme become widespread. Perhaps it's that sapphires are more common in the Earth's crust but that they are typically very thinly dispersed and not worth going after except in a handful of places where they occur in higher concentrations of larger and better stones?

Was Kingsolomon who found the sapphire in the rock, I was there when he found it too, we were at Black Springs.

I don't know if it's the host rock where the stone formed or whether the rock attached itself somehow but it's a nice find. I thought the rock is ilmenite but not so sure now. Though I'm sure Goldierocks would have a better idea than me. In the first pic there is also a smaller sapphire below the larger one. The whole specimen rock and all is about thumb size, maybe a touch larger.

If it's ilmenite it makes me wonder if the titanium iron oxide is where the stones derive their colour from??

https://www.prospectingaustralia.com/forum/img/member-images/487/1523671589_20141008_131816.jpg
https://www.prospectingaustralia.com/forum/img/member-images/487/1523671589_20141008_131844.jpg

Ah yes, that's the one. Barney/King Solomon found it though he didn't say where at the time.

Pretty interesting. It's the only one like that I've seen with my own eyes. 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. Given that it's one of the worlds major sapphire-producing fields and has seen tens of thousands of miners both small and large digging there for over a century, it's clearly a rare phenomenon in my area at least.

 

[Lefty]

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.

 

[Lefty]

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.

 

[Mungoman]

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.

 

[user 4386]

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.

 

[user 4386]

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.

 

[deadpan]

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.

 

[Heatho]

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.com/2.54ct-madagascar-emerald-cut-blue-sapphire-b6272-/

https://www.diamondimports.com.au/Round-Brilliant-Cut-Diamond-2029ct-J-VS1-RBC1271.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.

 

[Lefty]

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.

 

[user 4386]

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.com/2.54ct-madagascar-emerald-cut-blue-sapphire-b6272-/

https://www.diamondimports.com.au/Round-Brilliant-Cut-Diamond-2029ct-J-VS1-RBC1271.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).

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.

 

[user 4386]

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.