sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, exhibits various colors such as brown, white, and tan, vitreous to waxy luster, microcrystalline crystal structure, conchoidal fracture with no true cleavage, and specific gravity around 2.60 to 2.65.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, exhibits various colors such as brown, white, and tan, vitreous to waxy luster, microcrystalline crystal structure, conchoidal fracture with no true cleavage, and specific gravity around 2.60 to 2.65.
Formation & geological history
Formed mainly by the deposition of silica from groundwater in the cavities of igneous, metamorphic, or sedimentary rocks, often occurring in concentric bands.
Uses & applications
Widely used in jewelry, ornaments, polished lapidary specimens, and in industry for mortars and pestles due to its hardness.
Geological facts
Agate is one of the most popular and varied stones used in lapidary arts, with individual varieties named after their specific patterns and locations, such as fortification agate, moss agate, and Lake Superior agate.
Field identification & locations
Easily identified by its distinctive banded patterns and waxy luster; commonly found globally in volcanic rock cavities and river gravels, making it a favorite for rockhounds.
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