Rock & Mineral Encyclopedia

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

Banded Iron Formation

Ancient chemically deposited rock of alternating iron-oxide and silica bands recording Earth's early oxygenation and a major iron ore source.

A green ornamental stone, often serpentine-rich marble or verde antique, valued for its rich green color and white veining.

A pegmatitic granite in which quartz and feldspar intergrow to resemble ancient runic or Hebrew script.

Sandstone altered by metamorphism, with partly recrystallized quartz grains, transitional between true sandstone and quartzite.