Calcite, Chalcopyrite & Spahlerite
Calcite, a form of calcium carbonate, is a very common mineral found in many different geological settings. It is usually white, clear or very pale pink or yellow. It can look very similar to quartz but is easy to distinguish because it fizzes when it reacts with dilute hydrochloric acid. Calcite often occurs in veins or as fracture coatings or filling void spaces. Where crystals have enough time and space to fully form, calcite has a distinct rhombic shape. Calcite is the main mineral in limestone, marble and chalk, and is widely used in construction, agriculture and pharmaceutical industries.
Chalcopyrite is the most common ore mineral for copper and is a sulphide of iron and copper. Chalco comes from the Greek word chalko, meaning copper. Chalcopyrite is commonly found in sulphide deposits in most ore-forming environments. A characteristic deep brass yellow colour and iridescent green-to-purple weathering surfaces distinguish chalcopyrite from gold and sulphides such as pyrite.
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. Although sphalerite is a relatively soft mineral, it can be cut (faceted) into attractive gems, which are used for mineral displays.
This sample comes from the Kinman Creek property south of Nimpkish Lake, about 50 km southeast of Port Hardy on Vancouver Island.
The sample is mostly brassy yellow chalcopyrite with small amounts of more silvery-yellow pyrite, sphalerite and calcite. It comes from a small copper porphyry type deposit, where an intrusive rock caused hot hydrothermal chemical solutions to circulate through the host volcanic rocks, forming veins with ore minerals as the solutions cooled. To date, no significant deposits have been found or mined in the Kinman Creek area.
Store: Association for Mineral Exploration (AME)
Accession #: AME 482
Primary Mineral: Calcite
Secondary Mineral: Chalocpyrite & Sphalerite
Site Locality: Kinman Creek
Location: Nimpkish Lake, British Columbia
Special Features: n/a