metamorphic
Beach Pebble (Nephrite Jade / Chalcedony)
Ca2(Mg,Fe)5Si8O22(OH)2 / SiO2
Hardness 6.0-7.0 on Mohs scale, waxy to vitreous luster, microcrystalline to cryptocrystalline structure, grayish-green color, sub-translucent to opaque, smooth water-worn surface.
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Physical properties
Hardness 6.0-7.0 on Mohs scale, waxy to vitreous luster, microcrystalline to cryptocrystalline structure, grayish-green color, sub-translucent to opaque, smooth water-worn surface.
Formation & geological history
Formed through low-grade regional metamorphism or silica precipitation in volcanic rocks, sub-rounded and smoothed over time by coastal wave action.
Uses & applications
Lapidary art, jewelry, tumbling, craft projects, decorative rock gardens, and amateur rockhounding collections.
Geological facts
Coastal beach pebbles undergo natural wave polishing over hundreds or thousands of years, smoothing down sharp edges and highlighting subtle internal patterns.
Field identification & locations
Identified by its smooth, water-rounded shape, cool feel, grayish-green coloration, and greasy to vitreous polish when wet. Commonly found along rocky coastlines like northern California, Oregon, and Washington.
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