Rock & Mineral Encyclopedia

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

Shale

The most common sedimentary rock, a fissile mudrock of compacted clay and silt that splits into thin layers.

A cream-colored spotted stone resembling a Dalmatian dog, made of feldspar and quartz dotted with dark mineral grains.

A silver-white iron arsenic sulfide and the most common arsenic mineral, known for striking sparks and a garlic smell when struck.

A general term for light-colored, fine-grained volcanic rocks rich in quartz and feldspar, like rhyolite.

Clear quartz filled with mineral inclusions that look like underwater gardens, mossy landscapes, or floating scenery.

Tabular quartz crossed by a milky white thread-like line marking where the crystal repeatedly cracked and re-healed.

Quartz colored blue by inclusions of the mineral dumortierite, giving a denim-like blue ornamental stone harder than dumortierite alone.

A white chalcedony filled with green or black dendritic, tree-like mineral inclusions that resemble ferns or moss frozen in stone.

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