sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, exhibits translucent to opaque transparency, waxy to vitreous luster, cryptocrystalline structure with distinct banding patterns, and conchoidal fracture with no true cleavage.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, exhibits translucent to opaque transparency, waxy to vitreous luster, cryptocrystalline structure with distinct banding patterns, and conchoidal fracture with no true cleavage.
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the slow deposition of silica-rich groundwater solutions over millions of years.
Uses & applications
Widely used in ornamental jewelry, carved decorative objects, precision instruments (such as knife-edge balances), and heavily collected by lapidary enthusiasts.
Geological facts
Agate was named by Theophrastus, a Greek philosopher, after the Achates River in Sicily where these stones were found in antiquity. Ancient civilizations valued agates for amulets and seals.
Field identification & locations
Identified by its characteristic concentric or parallel bands of color, waxy luster, and high hardness that scratches glass. Commonly found in regions with volcanic activity worldwide.
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