Quartz and Silver
Torbit Silver Mine. Alice Arm, British Columbia
Quartz is the second most abundant mineral on Earth, present in many different types of rocks. Although usually clear or milky white in colour, quartz is found in a variety of colours due to impurities in the crystal structure. Pure quartz consists of silicon and oxygen only, but atoms of other elements often make their way into the quartz crystal structure, colouring the crystals. Some varieties of quartz, like purple amethyst and yellow citrine, are considered to be semi-precious gemstones and have been used since ancient times to make jewellery and decorative objects. Well-formed (euhedral) crystals of quartz have a hexagonal cross section and are highly collectible.
Silver is an important precious metal. It is still highly valued today and has many important uses, as well as being used for jewellery. Silver has the highest electrical and thermal conductivity and reflectivity of all metals and is widely used in electronics and industrial chemistry. It is also used to make mirrors, photographic and x-ray film and collectible coins. Silver has natural antiseptic properties, therefore, has many different medical applications. Silver can occur in its elemental form as metallic silver, or in compounds and minerals with other elements like gold and lead. Silver has a distinct silver-grey colour and is soft and malleable, meaning it can be easily worked and shaped.
This sample comes from the Torbrit mine about 25 km north of Alice Arm in northern BC. The Torbrit mine was open from 1928 to 1959. In that time it produced 1,251,339 tonnes of ore containing 463.47 grams per tonne silver, 0.00538 grams per tonne gold, 0.389 per cent lead and 0.0441 per cent zinc. Most of this ore was mined in the last 10 years of the mine’s life.
The Torbrit orebody is relatively thin and flat. It follows a horizon of volcanically-derived sediments about 60 m thick for over 300 m in length. Sphalerite, galena and pyrite are the most abundant sulphide ore minerals in the Torbrit deposit. Silver was the main commodity produced by the mine, with lesser amounts of gold. The main gangue (waste) minerals are quartz, seen here, and barite.
Store: Association for Mineral Exploration (AME)
Accession #: AME-554
Primary Mineral: Silver
Secondary Mineral: Quartz
Site Locality: Torbit Silver Mine
Location: Alice Arm, British Columbia
Special Features: n/a