Rock & Mineral Encyclopedia

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

White Agate

A white to grayish banded chalcedony, the natural base color of much agate and the substrate for many dyed stones.

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

Tourmaline displaying two distinct colors in a single crystal, a natural color-zoning effect that makes each stone unique.

An exceptionally coarse-grained igneous rock, often granitic, famous for hosting large crystals and many gemstones.

Phosphate-rich sedimentary rock, the world's main source of phosphorus for fertilizers, formed in nutrient-rich marine settings.

A heavy, lead-grey metallic mineral with perfect cubic cleavage, galena is the world's main ore of lead and often carries silver.

A fine-grained, dark volcanic rock that erupts as fluid lava and forms most of the ocean floor and many lava plateaus.

A dense, coarse-grained ultramafic rock rich in olivine that makes up most of the Earth's upper mantle.

A black-and-white striped chalcedony-quartz rock whose bold zebra-like banding makes it a popular ornamental and lapidary stone.

A rare breccia formed by meteorite impact, containing shocked rock fragments and glassy melt blobs welded together.

A family of sheet silicate minerals that split into thin, flexible, shiny sheets, giving rocks a sparkling, layered appearance.

The calcium end-member of the plagioclase feldspar series, a high-temperature mineral common in mafic rocks, meteorites and lunar samples.

A rare chlorine-bearing iron garnet-supergroup mineral, the ferric analogue of wadalite, formed in high-temperature combustion-metamorphic rocks.

A high-temperature potassium feldspar that forms glassy crystals in fast-cooled volcanic rocks, sometimes cut as a moonstone gem.

A sodium-rich alkali feldspar of sodic volcanic rocks, sometimes forming large glassy crystals and the blue-flashing feldspar in larvikite.