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GeneralColorless cassiterite from Bolivia
20th Feb 2012 04:28 UTCSteve Stuart Expert
Also on the specimen are these off-white or tan needles. What might they be?
Thanks!
Steve Stuart
20th Feb 2012 04:35 UTCAlfredo Petrov Manager
20th Feb 2012 07:50 UTCKeith Compton 🌟 Manager
Firstly all I can say is that I would love to acquire such a piece.
As Alfredo states it is surprising that more is not found. I suggest that the answer to that is that it is simply misidentified. It is not expected to be clear. May even be thought of by miners, at first glance, as valueless Quartz. Some of the recent Chinese material is very transparent - though I have not seen colourless - perhaps some will show up. It doesn't make it more valuable per se just very unusual.
Cheers
20th Feb 2012 10:00 UTCGeorge Eric Stanley Curtis
I live in Cornwall, with tin mines everywhere all around me, and cassiterite is fairly common.
I can confirm that colourless cassiterite does exist, though not as frequently found as the brown stuff.
All the best
Eric
21st Feb 2012 03:50 UTCSteve Stuart Expert
Steve
21st Feb 2012 04:59 UTCNoah Horwitz
21st Feb 2012 05:14 UTCAlfredo Petrov Manager
26th Feb 2012 01:39 UTCSteve Stuart Expert
Thanks!
Steve
26th Feb 2012 04:37 UTCAlfredo Petrov Manager
26th Feb 2012 05:28 UTCSteve Stuart Expert
26th Feb 2012 11:16 UTCBart Cannon
Back in the late 1950s a 25 pound pure lump of cassiterite was brought in to the U.S. Bureau of Mines Seattle Office.
It was found by a road grater operator near the Monroe, Washington city dump. The noise of the encounter was loud enough that the grator operator got out of his cab and pulled the specimen out of the road bed, and he delivered to the USBM where the late Elwin Magill identified it as cassiterite.
Since tin was a strategic metal at that time, he initiated a very detailed prospecting program to find its source. Careful and exhaustive stream sediment prospecting was conducted all up and down the nearby drainages. Nothing but a trace of tin in a roadcut near Skyomish was ever found.
The source of that boulder remained a mystery until around 1990 when Larry Jeffers, owner of a mineral shop in Seattle's Pioneer Square named Semantics Underground showed me a flat of cassiterites from Tin City, Alaska.
BINGO ! That was the stuff ! Light brown cassiterites grading to colorless exactly like the piece that Magill had saved on his dusty shelf.
The theory was that 60 years ago a miner returned to Monroe from Alaska had tossed out a lump of cassiterite into the Monroe city dump.
And thus another example of the scourge of field collectors was born. Specimen dumping hundreds of miles from their true source.
Just like back in 1965 when my little brother found an amazonite cluster on top of the dump of the Ibex Mine in Leadville, Colorado.
Pack dumping. It's a problem. But haven't we all done it?
p.s. I sell that colorless cassiterite as a electron probe reference material to this day. Better than synthetic tin oxide.
~Bart
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