Rock & Mineral Encyclopedia

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

Snake Skin Agate

A chalcedony with a distinctive scaly, reptile-skin surface texture, typically in pale tan, pink, and gray tones.

A mica schist containing bladed blue kyanite crystals, a marker of medium- to high-grade metamorphism of aluminous rocks.

Natural volcanic glass speckled with embedded mineral crystals (phenocrysts) such as feldspar or cristobalite that grew before the lava chilled.

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

Natural emerald crystals still embedded in their host rock, prized as mineral specimens that show how the gem grew in place.

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.

Siderite is an iron carbonate ore, a brown rhombohedral mineral of the calcite group found in sediments and veins.

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

Wolframite is the historic principal ore of tungsten, a heavy black tungstate forming bladed crystals in granite veins.

Black volcanic glass laced with delicate web-like veins of contrasting color, formed by flow banding and fine crystallization.

A rounded sedimentary nodule cracked internally and filled with veins of yellow calcite, prized for its striking dragon-skin patterning.

A jasper crossed by fine dark veins forming a spiderweb-like network, often a brecciated stone cemented by darker matrix.

A dark, glassy rock formed when frictional heat from fault movement or impact melts rock along narrow veins.

Precious opal that forms in thin veins within brown ironstone boulders, cut with the host rock left as a natural dark backing.