Tremolite

Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2Mg5Si8O22(OH)2. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades to dark green with increasing iron content. It has a hardness on Mohs' scale of 5 to 6.

A fibrous variety of tremolite is used as asbestos. This material is toxic and inhaling the fibers can lead to asbestosis, lung cancer and mesothelioma. One of the two minerals of the gemstone jade is nephrite, a green variety of tremolite.

Tremolite is an indicator of metamorphic grade since at high temperatures it converts to diopside. Calcite, grossular, talc, and serpentine are common associates of tremolite.