Rock & Mineral Encyclopedia

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

Orbicular Granite

A rare granitic rock containing concentric, onion-like spheres called orbicules, prized as a striking ornamental stone.

A granite-like rock containing orthopyroxene, formed at high temperatures and pressures and often classed with the granulites.

An orbicular jasper with red and orange flower-like spots resembling poppies, famously from Morgan Hill, California.

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

A multicolored orbicular chalcedony from Madagascar famous for its circular eye-like orbs in greens, pinks, whites, and yellows.

A striking platy, blade-like variety of albite feldspar that grows in fanned aggregates of thin white crystals within granite pegmatites.

A hydrated volcanic glass with pearly, onion-like concentric cracks that pops into lightweight white granules when heated.

A hard, fine-grained siliceous rock with a dull porcelain-like texture, intermediate between soft diatomite and dense chert.

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