sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness: 6.5-7 on the Mohs scale; Color: Variable, often white, grey, blue, yellow, or brown with banded patterns; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None
- Hardness
- 6
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on the Mohs scale; Color: Variable, often white, grey, blue, yellow, or brown with banded patterns; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None
Formation & geological history
Formed through the deposition of silica from groundwater in the cavities of igneous, sedimentary, or metamorphic rocks over millions of years.
Uses & applications
Used in ornamental objects, jewelry, carvings, and industrial abrasive tools.
Geological facts
Agate is one of the most popular stones used in art and lapidary work. Ancient civilizations valued it for amulets and seals due to its toughness against acids.
Field identification & locations
Identified by its distinctive concentric banding and waxy luster. Found worldwide, particularly in volcanic rock cavities.
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