gemstone
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, exhibits banded or irregular patterns of color, waxy to vitreous luster, cryptocrystalline crystal structure, specific gravity of 2.58 to 2.64.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, exhibits banded or irregular patterns of color, waxy to vitreous luster, cryptocrystalline crystal structure, specific gravity of 2.58 to 2.64.
Formation & geological history
Forms primarily within the cavities of volcanic rocks (vugs or vesicles) and metamorphic rocks through the slow deposition of silica-rich groundwater solutions over millions of years.
Uses & applications
Widely used in jewelry, ornamental carvings, decorative objects, and industrial applications requiring durable precision edges or mortars and pestles.
Geological facts
Agate has been used by humans for thousands of years, dating back to the Neolithic period for making tools and ornaments, and was highly prized by the ancient Greeks and Romans for intaglio rings and seals.
Field identification & locations
Easily identified by its distinctive concentric banding and translucent to opaque appearance. Found worldwide, with notable deposits in Brazil, Uruguay, India, Madagascar, and the United States (such as Oregon and Lake Superior regions).
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