Named after the Tremola Valley in Switzerland, where it was first identified. A calcium-magnesium mineral of the amphibole group, most commonly found within metamorphosed limestone—marble.

Mineralogically, tremolite can occur as a form of asbestos. But the material used as a gemstone is the dense, massive variety, structurally distinct from the fibrous form. Same mineral name, entirely different character depending on crystal habit.

Little known as a gemstone, yet significant as an index mineral. Its presence reveals what temperature and pressure shaped the surrounding rock. Inconspicuous, but far from silent.