Rock & Mineral Encyclopedia

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

Howlite

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

A dark gray-to-black feldspar variety of moonstone that shows blue and white adularescent flash against a smoky body.

A pale jasper crossed by distinctive blue-gray veins or lines, valued by lapidaries for its calm color contrast.

A dark gray copper sulfide that is one of the richest copper ores, prized by collectors when found as rare sharp crystals.

Also called Sci-Fi Jasper, a Mexican jasper-rhyolite with swirling abstract patterns in cream, tan, gray, pink, and green.

The principal iron ore, a heavy iron oxide ranging from metallic silver-gray to earthy red, always leaving a tell-tale red-brown streak.