mineral
Agate
Cryptocrystalline quartz, SiO2
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale. Color: Highly variable, this specimen shows grey, brown, and purplish tones with banding. Luster: Vitreous to waxy. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Highly variable, this specimen shows grey, brown, and purplish tones with banding. Luster: Vitreous to waxy. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture).
Formation & geological history
Forms primarily in cavities of volcanic and metamorphic rocks from silica-rich fluids deposited in layers over time.
Uses & applications
Used widely in jewelry, lapidary arts, ornaments, and as a collector's item. Also historically used for precision pendulums and mortars/pestles due to hardness.
Geological facts
Agate was given its name by Theophrastus, a Greek philosopher, who discovered the stone along the shoreline of the river Achates.
Field identification & locations
Identified by its distinctive banding patterns, translucency (especially on edges), and waxy luster when polished. Found worldwide, with notable deposits in Brazil, Uruguay, and the USA.
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