mineral
Grey Agate (Tumbled)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 on the Mohs scale; Color: Grey with white banding; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58–2.64.
- Hardness
- 6
- Color
- Grey with white banding
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on the Mohs scale; Color: Grey with white banding; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58–2.64.
Formation & geological history
Formed primarily in volcanic and metamorphic rocks as a Result of silica deposition from groundwater filling cavities (vugs) in host rock.
Uses & applications
Used in gemstone carvings, jewelry (pendants and beads), ornamental home decor, and historically for precision tools like mortar and pestles due to hardness.
Geological facts
Agate is a variety of chalcedony. The name 'agate' was given by Theophrastus, a Greek philosopher, who discovered the stone along the shore of the Dirillo River in Sicily.
Field identification & locations
Identify in the field by its waxy luster, conchoidal fracture, and characteristic banding patterns. Commonly found in Brazil, Uruguay, and the Lake Superior region of the USA.
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Mineral/Rock
Banded Gneiss (River Rock/Pebble)
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Green Apatite on Albite
Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]
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Epidote
Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)
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