Lapis Lazuli is a beautiful semi-precious gemstone that features indigo-blue Lazurite, golden Pyrite and white Calcite. The deep-blue coloring is from Lazurite, the metallic gold sparkles are from Pyrite, and the white veining is from Calcite. Lapis (for short) is formed from metamorphic processes, and has been prized for its intense deep-blue color and use as a semi-precious stone since antiquity.
Lapis Lazuli does not have a crystal system since it is technically a rock, a metamorphic rock. Since the vast majority of Lapis is Lazurite, a mineral, and is consistently combined with minor Pyrite and Calcite minerals, it can casually lean either way. I choose to categorize it in the mineral section because of its consistency in composition, color and occurrence. And most of all, convenience. I don’t know where else I’d put it . . .
Quality Lapis Lazuli is found in limited localities, the most prolific, by far, being Afghanistan.