Esfalerita
Esfalerita is a mineral with formula ZnS. This specimen comes from Mina Troya, Mutiloa, Gipuzkoa, Euskadi, España and joined the Terrium collection in 2011.
Description
Enormous floater, cabinet size, near-museum, no damage, with a very rich paragenesis: dolomite on sphalerite with many thousands of minute pyrite crystals speckling the surface of the piece.
History of this specimen
I reserved it secretly to give it to Óscar. The piece I paid the most for at the 2025 La Unión fair.
About Esfalerita
Sphalerite, or blende, is the principal ore of zinc. At Áliva it was mined together with galena and pyrite as ores of lead and iron respectively. Its colour depends on chemical composition: iron content dictates the shift to dark tones, while trace elements such as mercury, copper or bismuth determine variations in colour.
About the locality
Mine worked by Exminesa between 1986 and 1993; operations ceased after a collapse in its underground gallery more than one kilometre long. The deposit was noted for large geodes that produced some of the best sphalerites from Spain, especially valued for their transparency and "honey-cognac" tones. Since 2009 the workings have remained closed and flooded, with only the tailings pond preserved as a vestige of its former lead and zinc production.
Technical data
- Catalogue No.
- 0632
- Composition
- ZnS
- Name
- Esfalerita
- Category
- Cupidium
- Matrix
- Roca oscura
- Associations
- dolomita cuarzo pirita
- Mine
- Mina Troya
- District / Municipality
- Mutiloa
- Province
- Gipuzkoa
- Region
- Euskadi
- Country
- España
- Acquired
- 2011
- Ex-collection
- David Martínez
- Etymology
- From the German "Blende", meaning 'deception', for its resemblance to galena but lacking lead.
- Quality
- Top
- Value trend
- Al alza
Related specimens
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- Abernathyita — España
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- Aerenita — España
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- Ágatha — Brasil
- Analcima — España