mineral

Quartz and Slate Pebbles

Silicon Dioxide (SiO2) and Metamorphosed Shale/Mudstone

Hardness: 7 (Quartz) and 2.5-4 (Slate); Color: white to off-white (quartz) and dark gray to black (slate); Luster: Vitreous to dull; Crystal structure: Hexagonal/Trigonal (Quartz) vs Foliated (Slate).

Hardness: 7 (Quartz) and 2
Color: white to off-white (quartz) and dark gray to black (slate)
Luster: Vitreous to dull

Identified July 18, 2026More mineral →

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Physical properties

Formation & geological history

Quartz forms from cooling magma or hydrothermal veins. Slate forms from the regional metamorphism of clay-rich sedimentary rocks under low heat and pressure. These specimens appear to be river or beach tumbled pebbles.

Uses & applications

Landscaping, construction aggregate, decorative stone, and educational collecting. Small pebbles like these are often used in aquariums or garden pathways.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Slate is highly valued for its ability to be split into thin, flat sheets, which is why it has been used for centuries as roofing material.

Field identification & locations

Identify in the field by checking hardness (quartz will scratch glass; slate is softer and often has a platy/layered texture). Commonly found in stream beds, beaches, and glacial till.

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