sedimentary
Agate
SiO2 (Chalcedony / Quartz)
Hardness of 6.5-7 on the Mohs scale, typically exhibits white, gray, brown, and blue banding, waxy to vitreous luster, microcrystalline crystal structure, conchoidal fracture, and specific gravity of 2.6-2.7.
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Physical properties
Hardness of 6.5-7 on the Mohs scale, typically exhibits white, gray, brown, and blue banding, waxy to vitreous luster, microcrystalline crystal structure, conchoidal fracture, and specific gravity of 2.6-2.7.
Formation & geological history
Formed through the deposition of silica from groundwater in the cavities of ancient volcanic or sedimentary rocks, often developing in concentric layers over millions of years.
Uses & applications
Commonly used in ornamental carvings, jewelry, polished decorative slabs, and as collector specimens.
Geological facts
Agate is one of the most popular stones used in lapidary art and has been prized since ancient times, notably in ancient Greece and Rome for seals, rings, and vessels.
Field identification & locations
Easily identified by its distinctive concentric or parallel banding and waxy luster. Found worldwide, with notable deposits in Brazil, Uruguay, India, Madagascar, and the United States.
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Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
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Sedimentary Sandstone
Arenite (Sedimentary Rock)
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Quartz pebble
Silicon dioxide (SiO2)
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Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
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Banded Siltstone / Mudstone Pebble
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