The Geometry of Mineral Crystals

There are many, many different crystal shapes in the world. In fact, there are too many to list in a simple blog post! Determining the shapes of different minerals can help you uncover their identity.

Staurolite Twins

Staurolite is a silicate mineral which occurs in metamorphic rocks and is often found with the minerals kyanite and garnet. Staurolite is a 7 to 7.5 on the Mohs Hardness Scale which has a range from 1 (softest) to 10 (hardest), has a glassy to resinous luster and a colorless streak. Prismatic crystals of staurolite are common and often found twinned.