Calcite is a soft carbonate mineral that is found as both veins and as the primary mineral in limestone and marble. When in limestone it can host fossils and forms in a deep sea environment. It is also ground up and used in lawncare to raise the pH of acidic soil in the product called lime. When in veins it is often found with quartz.
Bornite is an important copper ore mineral found in many different types of copper deposit. It is also known as peacock ore because of its iridescent purple-blue-green tarnish. Fresh bornite, however, is copper red. Bornite commonly occurs with other copper sulphide minerals such as chalcocite and weathers, or “oxidizes”, to malachite.
The Bethlehem deposit is one of the deposits that make up the Highland Valley Copper mine, which also includes the Lornex, Highmont and Valley deposits. Early prospectors found copper mineralization in the Highland Valley area in the late 1800s and started hand mining at the Snowstorm and Iona zones of the Bethlehem deposit in 1907, when a wagon trail was built to nearby Ashcroft and the Fraser Canyon railway line. Large-scale open pit mining started at Bethlehem in 1962 and continued until the early 1980s, when production shifted to the other deposits, which are still being mined today. The large Valley pit and operations are visible from a lookout on Highway 97C.
The main ore minerals at the Bethlehem deposit were bornite and chalcopyrite, and bornite is seen in this sample. The ore minerals are mainly in very narrow veins, often only a few millimetres wide. Chalcopyrite is also found as fine “disseminations”, or speckles, throughout the host granodiorite rock. Pyrite is also common at Bethlehem, mainly towards the outer edges of the deposit. The other ore mineral mined at Bethlehem was molybdenite, another sulphide mineral and the main ore for molybdenum, which also occurs in narrow veins with quartz.
From 1962 to 1982, production at the Bethlehem mine totalled 96,324,510 tonnes of ore that yielded 99,826,893 grams silver, 1,279,833 grams gold, 398,112,545 kilograms copper and 851,048 kilograms molybdenum.
Store: Association for Mineral Exploration (AME)
Accession #: AME-8
Primary Mineral: Calcite
Secondary Mineral: Bornite
Site Locality: Bethlehem Mine
Location: Highland Valley(North), British Columbia
Special Features: n/a