Ilvaite - CaFe₃O[Si₂O₇](OH)

Habit: Iron black or dark grayish black. Crystals short to long prismatic, commonly striated vertically; also coarsely crystalline, massive or granular. Submetallic luster; opaque, but translucent in thin fragments. Brownish black streak.

Environment: Occurs in contact metasomatic iron, zinc and copper ores, as well as in sodalite syenites and associated with zeolites.

Etymology: Named for the location of its discovery — Elba, Italy — which was called Ilva in Latin.