This prehnite crystal plate is from the Kayes Region, Mali. Areas of this region have been prolific producers of these mineral specimens, for collection, off and on for years. Diggings and small mines are operated by locale communes and villages. This specimen consists of stacked, ball shaped, formations, or botryoidal aggregates of crystals. Prehnite is a silicate mineral and contains the elements Ca, Al, Si, O, and H.