mineral
Water-worn chalcedony pebble
Chalcedony, microcrystalline SiO₂; possibly iron-stained agate
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; gray-blue and tan with a waxy to vitreous luster, translucent edges, and no visible cleavage. Microcrystalline quartz; the small pits and rusty patches may reflect weathering or iron-oxide inclusions.
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Physical properties
Hardness 6.5–7 Mohs; gray-blue and tan with a waxy to vitreous luster, translucent edges, and no visible cleavage. Microcrystalline quartz; the small pits and rusty patches may reflect weathering or iron-oxide inclusions.
Formation & geological history
Silica precipitated in rock cavities or fractures, then was rounded by water transport; its exact age and source cannot be determined from the photo.
Uses & applications
Used for beads, cabochons, carvings, and ornamental pieces; this small pebble is mainly a beginner’s or casual collector’s specimen.
Geological facts
Chalcedony is quartz too fine-grained to distinguish individual crystals without magnification and may occur in many colors.
Field identification & locations
Look for a smooth, waxy surface, hardness sufficient to scratch glass, and no fizz with dilute acid. Found in varied volcanic and sedimentary settings worldwide; photo alone cannot confirm the identification.
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