Talc quarry inspection. Worker inspecting a piece of talc rock in a talc quarry. Talc (hydrated magnesium silicate) is a very soft mineral that is the main component of talcum powder. After being quarried, the rock is crushed into powder form and is also used in paper, plastics, cosmetics and paints. This pile of talc is in the talc quarry in Luzenac, France, the largest talc quarry in the world. It is at an altitude of 1800 metres altitude in the Ariege region of France. Founded in 1905, it produces 400,000 tonnes of talc in a year.