Class : Silicates
    Subclass : Inosilicates
    Crystal system : Monoclinic
    Chemistry : Ca₂Mg₅Si₈O₂₂(OH)₂
    Rarity : Common

Tremolite is the magnesian pole of the tremolite-ferroactinolite series, the intermediate terms being designated by the general name of actinolite. It is a common calcic amphibole that is found mainly in dolomites and metamorphic limestones; more rarely, it derives from the regional metamorphism of ultrabasic rocks by transformation of forsterite or diopside; it is then associated with talc and antigorite. Its name comes from its locality of discovery : Val Tremola (Switzerland). Tremolite most often occurs in masses of fibrous crystals with a vitreous luster, more rarely in distinct crystals with a diamond-shaped section and measuring up to 25 cm, longitudinally striated and often curved. White when pure, tremolite is most often gray or greenish, exceptionally pink. The compact variety called "nephrite" is worked as an ornamental stone and marketed under the name of "jade". Fibrous tremolite is also used as an insulating material and as a chemical filter, uses in sharp decline since the discovery of the carcinogenic risk linked to these mineral fibers. Crushed tremolite is also used as a mineral filler and whitening agent in construction materials.

Main photo : Tremolite from Miners Bay, Ontario, Canada © David K. Joyce

Single or multiple twins parallel to {100} are common, and rarer on {001}.

No fakes listed for this mineral species.