Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Lapis Lazuli
An intensely blue metamorphic rock of lazurite flecked with golden pyrite, prized for millennia as a gemstone and ultramarine pigment.
metamorphic
Sodalite
A royal-blue feldspathoid mineral with white calcite veining, often confused with lapis lazuli but lacking its golden pyrite flecks.
mineral
Lignite
The lowest rank of coal, a soft brown carbon-rich rock formed from compacted peat, used mainly for electricity generation.
sedimentary
Greenschist
A green, foliated low-grade metamorphic rock colored by chlorite, actinolite, and epidote, marking the greenschist metamorphic facies.
metamorphic
Sideromelane
A transparent, pale brown basaltic volcanic glass formed when basalt lava is quenched extremely fast, often underwater.
igneous
Greenstone
A general field term for green, low-grade metamorphosed basaltic rocks colored by chlorite, epidote, and actinolite.
metamorphic
Boninite
A rare high-magnesium andesite formed in young subduction zones, named for Japan's Bonin Islands.
igneous
Chlorite Schist
A soft, green, foliated rock rich in chlorite, formed by low-grade metamorphism of mafic or volcanic rocks.
metamorphicSlate
A fine-grained, low-grade metamorphic rock that splits into flat sheets along slaty cleavage, long used for roofing and flooring.
metamorphic
Adularia
A low-temperature potassium feldspar famous for forming transparent Alpine crystals and the gem moonstone, which shows a floating blue sheen called adularescence.
mineral