Rock & Mineral Encyclopedia

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

Serpentinite

A green, often mottled metamorphic rock formed by the hydration of mantle rocks, soft and waxy with a smooth, slippery feel.

A vivid copper-bearing Mexican stone of red cuprite and green chrysocolla that evokes a desert sunset.

The fine-grained volcanic equivalent of monzonite, an intermediate lava with nearly equal feldspars and little free quartz.

A treated chalcedony with a network of crackled veins, usually heated and dyed in vivid colors for affordable, eye-catching beads.

A yellow-brown alteration material formed when basaltic volcanic glass reacts with water, common in hydrovolcanic tuffs and pillow lavas.

A patterned common opal with mottled, leopard-like spots and blotches, prized as an ornamental and cabochon stone.

A chalcedony agate with red, orange, and yellow plume or banding patterns that rise like dancing flames within the stone.

A white, porous borate mineral webbed with gray-black veins, widely dyed to imitate turquoise and other stones.

A translucent agate whose mineral inclusions resemble miniature landscapes of trees, hills, and horizons within the stone.