Mineral Guides

Quick answer: Sulfur is both a chemical element and a mineral: native sulfur forms bright yellow crystals around volcanic vents

Quick answer: Selenite is the clear, crystalline variety of gypsum (hydrated calcium sulfate). It is so soft (2 on the

Quick answer: “Jade” is two different minerals: nephrite, an amphibole (tremolite-actinolite), and jadeite, a pyroxene. French mineralogist Augustin Damour showed

Quick answer: Malachite, a copper carbonate hydroxide, grows in concentric bands as copper-rich water deposits thin layers in cavities, and

Quick answer: Turquoise is a hydrated copper aluminum phosphate that forms where copper-rich water seeps through rock in arid climates.

Quick answer: Emerald, aquamarine, morganite, heliodor, and goshenite are all the same mineral: beryl, a beryllium aluminum silicate. Trace elements

Quick answer: Ruby and sapphire are the same mineral, corundum (aluminum oxide, Al2O3). Red corundum is ruby, colored by chromium;

Quick answer: Garnet is a group of related silicate minerals, not a single mineral. The main species are almandine and

Quick answer: Fluorite (calcium fluoride) gave its name to fluorescence: in 1852, physicist George Gabriel Stokes named the glow after

Quick answer: Pyrite (iron sulfide, FeS2) fooled prospectors because its brassy-yellow metallic shine resembles gold. Simple tests tell them apart: