Well formed, prismatic holmquistite crystals are unevenly distributed in a fine-grained, green, hornblende-rich amphibolite matrix. They may occur as individual crystals, or in clusters, often growing radially from the same point. When separated from the matrix, the crystals are semi-transparent and of a pinkish-bluish-violet color. The relative abundance between holmquistite and ferro-holmquistite has not been systematically studied, and ferro-holmquistite may be more common than holmquistite
Greenbushes Mine, Greenbushes tinfield, Bridgetown-Greenbushes Shire, Western Australia, Australia