sedimentary

Quartz Pebble with Host Rock / Schist Matrix

Silicon Dioxide (SiO2) with Metamorphic Host Rock

AI-generated identification · may be incorrect

Hardness: 7 for quartz portion, 3-5 for matrix; Color: Translucent yellowish-brown quartz with dark grey to black host rock band; Luster: Vitreous on quartz, dull to sub-metallic on host rock; Structure: Microcrystalline quartz with layered schist/shale inclusion;…

Hardness: 7 for quartz portion, 3-5 for matrix
Luster: Vitreous on quartz, dull to sub-metallic on host rock

Identified July 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when quartz veins filled fractures within metamorphic or sedimentary host rock. Subsequent weathering and stream erosion rounded the specimen into a pebble, leaving a band of dark host matrix embedded within the quartz.

Uses & applications

Commonly collected as river rocks, landscaping pebbles, and decorative stones. Small tumbled pieces are occasionally used in casual wire-wrap jewelry.

Geological facts

Quartz vein inclusions often capture slices of the country rock through which hydrothermal fluids originally flowed, offering a mini-cross section of the local geology.

Field identification & locations

Identify in the field by the hard, glass-like yellowish quartz body (scratches glass easily) contrasting sharply with the softer dark grey band. Found abundantly in riverbeds, glacial deposits, and gravel bars worldwide.