Molybdenite

Soft silvery-grey molybdenite is the main ore mineral for molybdenum. Molybdenum, often just called ‘moly’, is used to make alloys with other metals like iron. Adding molybdenum to steel makes it stronger, harder and more resistant to corrosion. It also has a very high melting temperature, so is very useful when added to alloys to make aircraft parts and industrial motors, which need to withstand high temperatures.

This sample of molybdenite is from the Boss Mountain mine in the Cariboo region of central BC. The Boss Mountain mine is on the eastern slopes of Big Timothy Mountain, about 43 km southeast of the small town of Horsefly.

First discovered in 1917, the Boss Mountain open pit mine was active on and off until 1983, when it finally closed due to low molybdenum prices. At its peak in 1961, estimated reserves were 1.4 million tonnes of ore with an average grade of 0.75% molybdenite.

The molybdenite at the Boss Mountain mine is found in quartz veins up to 30 cm wide. The veins are part of a type of mineral deposit called a porphyry deposit, which forms in and around certain kinds of intrusive rocks.