sedimentary

Quartz-veined Basalt or Limestone Pebble

Quartz vein in host rock (Silicate mineral in carbonate or volcanic matrix)

AI-generated identification · may be incorrect

Hardness varies from 3 (host rock) to 7 (quartz veins) on the Mohs scale; color is dark grey to black with contrasting stark white quartz veins; luster is vitreous on quartz and dull or earthy on the host rock; no distinct crystal structure visible due to water-worn tumbling; conchoidal fracture for quartz.

Identified August 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through hydrothermal activity where silica-rich fluids filled fractures in a pre-existing host rock, subsequently eroded, transported by water, and rounded into a pebble on a beach.

Uses & applications

Collectible beach stone, ornamental landscaping, or educational specimen.

Geological facts

Quartz veins are very common geological formations created when mineral-rich hydrothermal fluids circulate through cracks deep within the Earth's crust and precipitate minerals like quartz.

Field identification & locations

Easily identifiable in the field by the striking contrast of white quartz veins cutting sharply through a darker matrix rock. Found commonly in marine and river gravels worldwide.