metamorphic/igneous transition

Quartz Vein in Host Rock (Pebble)

Quartz (SiO2) with sandstone or siltstone matrix

Hardness: 7 (Quartz part), Color: White and Tan/Brown, Luster: Vitreous to dull, Crystal structure: Trigonal/Amorphous, Cleavage: None (conchoidal fracture), Specific Gravity: ~2.65

Identified April 3, 2026More metamorphic/igneous transition →

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Physical properties

Hardness: 7 (Quartz part), Color: White and Tan/Brown, Luster: Vitreous to dull, Crystal structure: Trigonal/Amorphous, Cleavage: None (conchoidal fracture), Specific Gravity: ~2.65

Formation & geological history

Formed through hydrothermal processes where mineral-rich hot water fills cracks in a host rock (like sandstone or shale). The white layer is the vein, while the brown part is the country rock. This specimen has been tumbled and rounded by water action (river or beach erosion).

Uses & applications

Primarily used as decorative stones, landscaping gravel, or as a pocket stone for amateur collectors.

Geological facts

Quartz veins often act as 'pathfinders' for precious metals like gold. This specific specimen is a 'water-worn pebble,' showing how nature can polish and round rocks over thousands of years.

Field identification & locations

Identify in the field by looking for the distinct color layering (the 'sandwich' look) and checking if the white part can scratch glass (indicating hardness of 7). Very common in riverbeds and mountainous glacial till.

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