Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Ruby

The red, chromium-colored variety of corundum, prized as one of the most valuable colored gemstones and second only to diamond in hardness.

A deep cranberry-red to purplish-pink variety of lithium-rich elbaite tourmaline, prized as a rich, saturated rubellite gemstone.

A rose-pink manganese silicate marbled with black veins, prized as a tough ornamental and occasionally faceted gemstone.

A striking rock of green zoisite studded with red-pink ruby crystals and black hornblende, also called anyolite.