Habit: Sea green, violet, purple, blue, pink, yellow, brown, white or colorless. Prismatic hexagonal crystals; also granular, globular to reniform, nodular or massive. Vitreous to subresinous luster; transparent to translucent. White streak.
Environment: Very common, occurring in all types of igneous rocks, marbles and skarns, especially in calcium-rich regional and contact metamorphic rocks. An essential component of sedimentary phosphorites.
Etymology: From the Greek apate, meaning "deceit," referring to its similarity to crystals of other minerals such as aquamarine, amethyst and olivine.