Discussions

╳Discussions

Groups

Recent Images in Discussions

PhotosCassiterite and Tourmaline

5th Sep 2019 11:07 UTCDale Foster Manager

Cassiterite, Tourmaline

Viloco Mine (Araca Mine), Loayza Province, La Paz, Bolivia

If you flip the piece over, you can clearly see many small, acicular greenish-black crystals of tourmaline. The association of the two minerals is not only rare from Viloco but anywhere in the mineral world.

I can't comment upon the Viloco deposit as I have neither visited or studied it.

However, I can comment that in Cornwall, the association of Cassiterite with Tourmaline is very common.

I have also done some collecting at the Rooiberg Mine site in South Africa and found a similar association to be present as well.

Just a few Cassiterite and Tourmaline examples from Cornwall:

Cassiterite

Bunny Mine, Stenalees, Treverbyn, Cornwall, England, UK

Cassiterite, etc.

Old Beam Mine, Bugle, Treverbyn, Cornwall, England, UK

Cassiterite, etc.

Bassett & Grylls Mine, Porkellis, Wendron, Cornwall, England, UK

Cassiterite, etc.

South Condurrow Mine, Grenville United Mines, Troon, Camborne, Cornwall, England, UK

5th Sep 2019 11:59 UTCPeter Nancarrow 🌟 Expert

I can second Dale's observation of the cassiterite/tourmaline association being very common in Cornwall, and it also occurs in Devon - e.g. at Hemerdon and at the Birch Tor & Vitifer Mines.

Pete N.

5th Sep 2019 15:37 UTCDale Foster Manager

Yes, should have said Devon as well.

Come to think of it just about every tin mine on Dartmoor would show a Quartz/Tourmaline/Cassiterite assemblage in its lode structures.

5th Sep 2019 13:14 UTCHarold Moritz 🌟 Expert

Cassiterite occurs in New England pegmatites, usually in the cleavelandite zone with the most diverse mineralogy, where tourmaline is also abundant. A few examples shown.

Cassiterite, etc.

Brack Gem prospect, East Glastonbury, Glastonbury, Hartford County, Connecticut, USA

Cassiterite, etc.

Noyes Mountain Quarry, Greenwood, Oxford County, Maine, USA

5th Sep 2019 17:59 UTCAlfredo Petrov Manager

Tourmaline with cassiterite is not particularly common in Viloco, but not that rare either. I have one piece of cassiterite from there with felty dark greenish brown tourmaline needles comprising the matrix, and another piece with tourmaline needles included in a transparent cassiterite crystal. Tourmaline needles with cassiterite also come from the Siglo XX tin mine, and the Huanuni mine. In fact the Siglo XX tin mine is one of the world‘s largest accumulations of tourmaline, tens of millions of tons, although most of it is rather tiny and nondescript.