sedimentary

Vein Quartz in Basalt or Chert

Silica-veined dark lithic rock (Quartz veins in microcrystalline matrix)

Hardness: 7 (for the quartz veins), 6-7 overall; Color: Dark gray to black with white quartz veins; Luster: Vitreous on veins, dull to waxy on matrix; Crystal Structure: Microcrystalline matrix with macrocrystalline quartz veinlets; Specific Gravity: ~2.65 - 2.75.

Hardness: 7 (for the quartz veins), 6-7 overall
Color: Dark gray to black with white quartz veins
Luster: Vitreous on veins, dull to waxy on matrix

Identified July 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the fracturing of a host rock (such as basalt, shale, or chert) followed by the hydrothermal precipitation of silica-rich fluids filling the cracks with white quartz, later weathered into a rounded pebble.

Uses & applications

Collector specimen, lapidary use for tumbling and small carvings.

Geological facts

Quartz veins are extremely common in various geological settings worldwide, acting as natural scars that heal faults and fractures in the Earth's crust.

Field identification & locations

Easily identified by the stark contrast of white quartz veins against a dark background matrix. Common in stream beds and beaches where rocks have undergone fluvial or marine transport.

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