metamorphic
Quartzite River Rock
Metamorphic Rock (Quartzite)
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 More 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.
