Rock & Mineral Encyclopedia

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

Mookaite Jasper

An Australian silicified radiolarite jasper in warm mustard, red, burgundy, and cream earth tones, found only in Western Australia.

A common coarse-grained intrusive rock like granite but richer in plagioclase than potassium feldspar.

A tough, dark, medium-grained igneous rock with the composition of basalt, common in dikes and sills.

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

Ilmenite is the world's leading source of titanium, a heavy iron-black oxide common in mafic rocks and black sands.

A soft pink banded chalcedony, occurring naturally in delicate hues and also commonly produced by dyeing.

An opaque blue variety of chalcedony jasper, less common than red or green forms, colored by mineral inclusions.

A hardened soil crust cemented by calcium carbonate, forming a tough whitish layer common in arid and semi-arid regions.

Grandite is an intermediate garnet between grossular and andradite, common in skarns and prized for vivid green to golden crystals.

The most common variety of quartz, milky white from microscopic fluid and gas inclusions, forming massive veins worldwide.

An ultramafic rock of olivine and clinopyroxene, a peridotite variety common as cumulate layers in mafic intrusions.

An extremely common calcium carbonate mineral that comes in nearly every color and shows strong double refraction in clear crystals.

A hydrous aluminum garnet (hydrogrossular) intermediate between grossular and katoite, common in altered calcium-rich and serpentinized rocks.

A yellow-brown alteration material formed when basaltic volcanic glass reacts with water, common in hydrovolcanic tuffs and pillow lavas.