Canadian Rockhound: Tertrahedrite/Tennantite

Tetrahedrite is a common copper mineral that forms in mesothermal and epithermal veins. It also forms with carbonatites, and in hydrothermal deposits. The name is derived from its crystal habit, being predomenantly tetrahedral. Tetrahedrite is soluble in nitric acid and aqua regia. ©1996 theImage.com

Tertrahedrite/Tennantite
By Richard Gunter

Tetrahedrite, (Cu,Fe)12Sb4S13, forms a series with tennantite, (Cu,Fe)12As4S13, and most natural crystals are intimate mixtures of the two minerals. The mineral terahedrite is often high in silver and has been mined for this metal in other parts of Canada (for example, the Equity Silver Mine. B.C.).

In Manitoba, the major source of tetrahedrite is the Chisel Mine, near Snow Lake. It is a common enough mineral that small amounts, usually in microscopic size, can be found in other copper-zinc mines in Manitoba, such as the original Flin Flon Mine.

The Chisel Mine, now closed, was a complex zinc-copper mine with several sulphosalt minerals found in small amounts. Tetrahedrite was more widespread than boulangerite or the other sulfosalts within the mine and was not always directly associated with the massive zin-copper ore. Tetrahedrite was most commonly found as iron-black, coarse grained masses, with 2 - 3 cm single crystal partings, in the center of late quartz veins. The quartz veins formed during the metamorphism of the Chisel Mine in areas of lower pressure, such as fold noses. Minor pyrite and chlorite were found in the quartz veins as accessory minerals. There are no recorded pockets in the quartz veins that produced crystals of tetrahedrite. As with boulangerite, tetrahedrite specimens will probably not be found on the dumps as the tetrahedrite contains significant silver values and was mined whenever it was found.

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The preceding article was first published in the February 1998 issue of The Mineral Vein, the official newsletter of the Mineral Society of Manitoba. Reprinted in the Canadian Rockhound with permission from the editor.