Rock Identifier
Weathered quartz-rich pebble, possibly iron-stained chalcedony (Microcrystalline quartz (SiO₂), likely chalcedony with iron-oxide staining) — mineral
mineral

Weathered quartz-rich pebble, possibly iron-stained chalcedony

Microcrystalline quartz (SiO₂), likely chalcedony with iron-oxide staining

AI-generated identification · may be incorrect

Brown-orange to gray, translucent at thin edges, with dull to waxy luster and irregular fracture; quartz hardness is about 7 Mohs, with no cleavage and specific gravity near 2.6. The surface appears naturally weathered rather than polished.

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Physical properties

Brown-orange to gray, translucent at thin edges, with dull to waxy luster and irregular fracture; quartz hardness is about 7 Mohs, with no cleavage and specific gravity near 2.6. The surface appears naturally weathered rather than polished.

Formation & geological history

Likely formed when silica-rich groundwater deposited chalcedony in a cavity, fracture, or volcanic host rock, followed by erosion and rounding in sediment. Exact geological age and source cannot be determined from the image.

Uses & applications

Common pieces are used as lapidary rough, tumbled stones, and decorative specimens; gem-quality translucent chalcedony may be cut for jewelry. This small irregular pebble has little industrial value.

Geological facts

The orange-brown coloration is probably caused by dispersed hematite or goethite. Its translucent edges and conchoidal-looking fracture are consistent with chalcedony, though the image cannot exclude weathered jasper or quartzite.

Field identification & locations

Test hardness against glass, which it should scratch, and inspect for a waxy texture and conchoidal fracture; a streak test may show little color unless iron oxides are abundant. Chalcedony and related quartz pebbles occur widely in volcanic terrains, gravels, and stream beds.