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Just wondering if anyone has been here looking for topaz or quartz? Is the designated fossicking site any good or are there better spots to look around?
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Topaz usually occurs in the tin veinsDave79 said:Been up there once. Headed up around the fossicking area and found heaps of water worn quartz but nothing was very good. Mostly dark, cloudy or fissured. Hundreds of old tin mines all around the area and apparently most of them can turn up nice quartz if you dig through the mullock heaps, not sure where the topaz is found.
goldierocks said:Topaz usually occurs in the tin veinsDave79 said:Been up there once. Headed up around the fossicking area and found heaps of water worn quartz but nothing was very good. Mostly dark, cloudy or fissured. Hundreds of old tin mines all around the area and apparently most of them can turn up nice quartz if you dig through the mullock heaps, not sure where the topaz is found.
So scope the creeks Lefty?Lefty said:It would be one of the first places I would scope out!
There is a sound geological reason - hot water cannot dissolve much tin, but if it has fluorine in it a lot can be dissolved and deposited elsewhere. The tin drops out as the oxide, cassiterite, and the fluorine crystallizes as things like fluorite and topaz (both fluorine minerals) at the same location.Lefty said:goldierocks said:Topaz usually occurs in the tin veinsDave79 said:Been up there once. Headed up around the fossicking area and found heaps of water worn quartz but nothing was very good. Mostly dark, cloudy or fissured. Hundreds of old tin mines all around the area and apparently most of them can turn up nice quartz if you dig through the mullock heaps, not sure where the topaz is found.
Every topaz occurance I've fossicked in far north QLD has been associated with an abandoned tin working.
goldierocks said:There is a sound geological reason - hot water cannot dissolve much tin, but if it has fluorine in it a lot can be dissolved and deposited elsewhere. The tin drops out as the oxide, cassiterite, and the fluorine crystallizes as things like fluorite and topaz (both fluorine minerals) at the same location.Lefty said:goldierocks said:Topaz usually occurs in the tin veinsDave79 said:Been up there once. Headed up around the fossicking area and found heaps of water worn quartz but nothing was very good. Mostly dark, cloudy or fissured. Hundreds of old tin mines all around the area and apparently most of them can turn up nice quartz if you dig through the mullock heaps, not sure where the topaz is found.
Every topaz occurance I've fossicked in far north QLD has been associated with an abandoned tin working.
Yes, that can occur.Lefty said:goldierocks said:There is a sound geological reason - hot water cannot dissolve much tin, but if it has fluorine in it a lot can be dissolved and deposited elsewhere. The tin drops out as the oxide, cassiterite, and the fluorine crystallizes as things like fluorite and topaz (both fluorine minerals) at the same location.Lefty said:goldierocks said:Topaz usually occurs in the tin veinsDave79 said:Been up there once. Headed up around the fossicking area and found heaps of water worn quartz but nothing was very good. Mostly dark, cloudy or fissured. Hundreds of old tin mines all around the area and apparently most of them can turn up nice quartz if you dig through the mullock heaps, not sure where the topaz is found.
Every topaz occurance I've fossicked in far north QLD has been associated with an abandoned tin working.
Yes, I found a few small bits of green and purple fluorite at one of the topaz sites.
Is the presence of fluorine the reason behind the scaly, beaten-up looking surface of the smoky crystals I found inside a hydrothermal pipe about a metre and a half long? The crystals inside the pipe had the look of something that had been dipped in acid (though many were very clean and clear inside) while the crystals just a foot away outside the pipe had bright, shiny faces like most of the Lowmead crystals. I read somewhere that fluorine can become concentrated in some hydrothermal pipes and attack the surface of quartz crystals in late-stage formation. Is this correct?
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