Opal

Sphalerite is the main ore mineral for zinc, and although relatively common, finding it in commercial amounts is somewhat rarer. The zinc will give the mineral a yellow or red hue, but iron can replace the zinc in the atomic structure, making the crystals black. Rarely, cobalt finds its way into the structure, and produces green crystals.

Opal is a mineraloid composed of amorphous silica. It is not considered a true mineral as it lacks an ordered atomic arrangement. This is due to the presence of water, differentiating it from crystalline silica (quartz). The internal structure of opal causes it to diffract light, producing pearly iridescence.

This sample is from the Treasure Mountain mine in the Tulameen River area, about 30 km northeast of Hope in southern BC. The sample is mainly red-brown sphalerite with opal filling in cavities.

The Treasure Mountain showing was discovered in the 1980s, when a silver-rich quartz-carbonate vein was found at the surface. Since then, several underground exploration shafts have been dug to test the extent of the veins. Mineralization is contained in polymetallic veins (veins that contain several different ore minerals and metals.) that mainly follow the Treasure Mountain fault that runs through the area. At Treasure Mountain, polymetallic veins contain sphalerite, an important source of zinc, as well as galena, the main ore mineral for lead, silver , and gold.

Specimen Information

Store: Pacific Museum of the Earth, University of British Columbia

Collection: UBC Geological Museum Collection

Accession #: S-74-761

Primary Mineral: Opal

Secondary Mineral: Sphalerite

Site Locality: Treasure Mountain Mine

Location: Tulameen, British Columbia

Special Features: n/a

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