gemstone
Moss Agate
SiO2 (Cryptocrystalline Quartz)
Hardness of 6.5 to 7 on the Mohs scale, green to blue-green moss-like inclusions of hornblende or chlorite within clear or milky chalcedony, vitreous to waxy luster, conchoidal fracture, specific gravity of 2.60 to 2.65.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, green to blue-green moss-like inclusions of hornblende or chlorite within clear or milky chalcedony, vitreous to waxy luster, conchoidal fracture, specific gravity of 2.60 to 2.65.
Formation & geological history
Forms from silicon-rich groundwater filling cavities or fractures in volcanic and metamorphic rocks, where microscopic quartz crystals precipitate out over long periods, often in hydrothermal environments.
Uses & applications
Commonly used for ornamental carvings, polished spheres, jewelry, and collector specimens.
Geological facts
Despite being called moss agate, it does not contain organic matter and is not a true agate in the strict sense (as it lacks concentric banding), but it is a chalcedony with dendritic or moss-like mineral inclusions.
Field identification & locations
Easily identified by its translucent to opaque chalcedony body containing striking green dendritic inclusions resembling moss or foliage; commonly sourced from India, the United States, Australia, and Russia.
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