Rock & Mineral Encyclopedia

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

Mocha Agate

A pale translucent chalcedony threaded with brown-black manganese and iron dendrites that mimic tiny ferns, mosses or landscapes.

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

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

Limonite is an amorphous brown iron oxide ore, the rust-colored material behind ochre pigments and bog iron.

A translucent apple-green chalcedony colored by nickel, the most prized green variety of the quartz family.

A brecciated, chatoyant quartz with swirling blue, gold, and brown fibers that shimmer like a stormy sky.

A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.

A trade name occasionally used for golden-yellow beryl (golden beryl or heliodor), the iron-colored yellow variety of the emerald mineral.

A banded variety of chalcedony quartz, famed for its colorful concentric layers and enormous range of patterns and colors.

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

Rutile is a major titanium ore and the famous golden needle inclusion that gives rutilated quartz its shimmering threads.

A warm mustard to brownish-yellow tourmaline, colored by iron or manganese, sitting between yellow and brown dravite tones.

A vivid blue-green hydrated copper silicate, soft on its own but prized as a gem when hardened by intergrown quartz or chalcedony.

Glacially transported banded agates found along Lake Huron's shores, typically small, frosted pebbles with red-orange iron banding.

A vivid yellow-and-black banded stone from Indonesian volcanic vents, colored by sulfur, arsenic minerals and iron oxides, not true jasper.