Quartz (var. agate)
Quartz (var. agate), Chihuahua, Mexico
Source: Smithsonian Natural History Museum, Washington, D.C.
Agate is a fine-grained variety of quartz known as chalcedony that shows concentric color banding. The colors in this agate are caused by microscopic inclusions of iron oxide minerals in the quartz. Agates are commonly found in cavities in volcanic rock, where silica-rich water deposited quartz crystals layer by layer parallel to the cavity wall.
Brazil is the major commercial source of agate.
Quartz (var. agate)
Quartz (var. agate), Chihuahua, Mexico
Source: Smithsonian Natural History Museum, Washington, D.C.
Agate is a fine-grained variety of quartz known as chalcedony that shows concentric color banding. The colors in this agate are caused by microscopic inclusions of iron oxide minerals in the quartz. Agates are commonly found in cavities in volcanic rock, where silica-rich water deposited quartz crystals layer by layer parallel to the cavity wall.
Brazil is the major commercial source of agate.