mineral
Moss agate (likely dendritic/chalcedony slab)
Cryptocrystalline quartz, SiO₂, with green amphibole or chlorite inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; dark green, white, and gray branching/cloudy patterns; vitreous to waxy luster; microcrystalline quartz with no obvious cleavage; specific gravity about 2.6. The irregular green inclusions resemble moss agate, though exact identification requires testing.
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Physical properties
Hardness about 6.5–7 Mohs; dark green, white, and gray branching/cloudy patterns; vitreous to waxy luster; microcrystalline quartz with no obvious cleavage; specific gravity about 2.6. The irregular green inclusions resemble moss agate, though exact identification requires testing.
Formation & geological history
Forms when silica-rich groundwater fills cavities or fractures, depositing chalcedony around manganese-, iron-, chlorite-, or amphibole-rich inclusions. Most specimens formed in volcanic rocks during the Cenozoic, though age varies by locality.
Uses & applications
Used for cabochons, carvings, polished slabs, ornamental objects, and mineral collecting; attractive material has modest jewelry value.
Geological facts
Moss agate is technically chalcedony rather than a true banded agate because its inclusions create moss-like patterns instead of concentric bands.
Field identification & locations
Identify by its translucent-to-opaque chalcedony body, green organic-looking inclusions, glassy/waxy surface, and hardness that scratches ordinary glass. Common sources include India, Brazil, Uruguay, the United States, and Australia; this rough slab may also be serpentinite or nephrite, which require hardness and specific-gravity tests to distinguish.
