mineral
Agate / Chalcedony Nodule
SiO2 - Silicon Dioxide
AI-generated identification · may be incorrectHardness 6.5-7 (Mohs), colors vary greatly but this specimen is brownish-orange to translucent gray, waxy to vitreous luster, cryptocrystalline structure.
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Physical properties
Hardness 6.5-7 (Mohs), colors vary greatly but this specimen is brownish-orange to translucent gray, waxy to vitreous luster, cryptocrystalline structure.
Formation & geological history
Forms in cavities of volcanic rocks or ancient lavas. Silica-rich fluids percolate through the rock, depositing layers of chalcedony.
Uses & applications
Used in lapidary arts, jewelry making, and collected by rockhounds.
Geological facts
Agates are formed from microscopic crystals of quartz. The translucent window in this specimen shows the typical chalcedony interior common in such nodules.
Field identification & locations
Can be identified by its waxy luster, conchoidal fracture, and translucency when held to light. Often found in riverbeds or beaches where weathering has released them from the host rock.
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