metamorphic

Quartzite River Rock

Metamorphic Rock (Quartzite)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: Purple, reddish-brown, and gray banding; Luster: Dull/Waxy (naturally weathered); Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture).

Hardness: 7 (Mohs scale)
Color: Purple, reddish-brown, and gray banding
Luster: Dull/Waxy (naturally weathered)

Identified July 13, 2026More metamorphic →

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Physical properties

Hardness: 7 (Mohs scale); Color: Purple, reddish-brown, and gray banding; Luster: Dull/Waxy (naturally weathered); Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen shows significant rounding and smoothing due to fluvial (river) or glacial transport over thousands of years.

Uses & applications

Primarily used as decorative landscaping stone, drainage aggregate, and in heavy construction; high-quality specimens are used for lapidary tumbling.

Geological facts

Quartzite is so durable that it often survives multiple weathering cycles better than its parent sandstone. The purple/red hues are caused by trace amounts of iron oxide (hematite) within the rock matrix.

Field identification & locations

Look for a sugary, crystalline texture when broken and a hardness that can easily scratch glass. Commonly found in riverbeds, glacial moraines, and weathered outcrops globally.