Rock & Mineral Encyclopedia

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

Blood Agate

A deep red banded agate colored by iron oxides, valued as a vivid red lapidary and jewelry stone.

A dark, foliated schist rich in graphite that leaves a grey-black mark and forms from metamorphosed carbon-rich sediments.

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

A jasper made of angular fragments naturally cemented back together, typically showing red and brown pieces in a quartz matrix.

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

A pink, manganese-rich variety of zoisite used as an ornamental gemstone, often mottled with white quartz and grey matrix.

A foliated metamorphic rock dominated by quartz with enough mica to give it a schistose, splitting fabric.

A clean, mature sandstone made almost entirely of quartz grains, representing extreme weathering, sorting, and recycling of sediment.

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

A banded, metamorphosed iron formation in which bright red jasper alternates with silvery hematite or magnetite layers.