mineral
Chalcedony (Agate / Quartz Pebble)
Microcrystalline Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectMohs hardness 6.5-7; waxy to vitreous luster; milky white to yellowish-tan; conchoidal fracture; no cleavage.
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Physical properties
Mohs hardness 6.5-7; waxy to vitreous luster; milky white to yellowish-tan; conchoidal fracture; no cleavage.
Formation & geological history
Formed through low-temperature precipitation of silica-rich fluids in cavities of volcanic or sedimentary rocks, then water-worn into a smooth pebble.
Uses & applications
Commonly tumbled for lapidary art, jewelry, ornamental carvings, and collector specimens.
Geological facts
Its yellowish hues often come from trace iron oxide impurities dispersed within the microfibrous quartz structure.
Field identification & locations
Identify by its hardness (scratches glass), waxy feel, translucency under backlighting, and smooth, water-eroded contours found in gravel beds and beaches worldwide.
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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Granite
Granite (Phaneritic intrusive igneous rock)
igneous