Rock & Mineral Encyclopedia

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

Platinum

A dense, durable, silvery-white precious metal that resists corrosion, used in fine jewelry and catalytic converters.

Ancient chemically deposited rock of alternating iron-oxide and silica bands recording Earth's early oxygenation and a major iron ore source.

Idaho's official state gem: a dark almandine garnet showing a four- or rare six-rayed star from oriented rutile inclusions.

A brassy copper-iron sulfide that is the world's most important copper ore, often showing colorful iridescent tarnish.

A rare almandine garnet that displays a four- or six-rayed star (asterism) from oriented rutile inclusions; the state gem of Idaho.

The most common garnet, an iron aluminum silicate in deep red to brownish-red hues, used as a gem and an industrial abrasive.

A trade term for orange garnets, mainly manganese-rich spessartine and the brownish hessonite variety of grossular.

The colorless variety of beryl, named after Goshen, Massachusetts, prized for its purity, clarity, and durability.

A collectible Oregon plume and scenic agate with feathery red and gold inclusions suspended in translucent chalcedony.

A Mexican banded agate famous for tightly swirling, contorted lacy patterns in warm reds, creams, and golds.

A plagioclase feldspar famous for labradorescence, a dramatic flash of iridescent blue, green, and gold across a dark gray stone.

A vividly banded fortification agate from Argentina prized for its bold red, gold and white concentric patterns.

A vividly swirling banded agate from northern Mexico with intricate looping patterns in warm reds, golds and creams.

A dark, mineral-rich dike rock with abundant mica or amphibole phenocrysts set in a fine groundmass, often associated with gold and diamonds.

A warm earth-toned jasper from Madagascar in flowing reds, oranges and golds, also called desert jasper, discovered in the early 2000s.