Habit: Colorless, pale yellow, pink, red, gray or green. Prismatic crystals elongated in one direction, often striated; may be granular, massive or fibrous. Vitreous luster; transparent to translucent. Grayish white streak.
Environment: Occurs in regional metamorphic rocks, particularly in greenschist and epidote-amphibolite facies, pegmatites and veins. Also found in acid igneous rocks contaminated with calc-silicate material.
Etymology: From the crystal system, which is a monoclinic dimorph of zoisite.