metamorphic
Orange Quartzite (River Pebble)
Quartzite (SiO2 with iron oxide inclusions)
Hardness: 7 on Mohs scale; Color: Honey-orange to yellow (due to hematite or goethite staining); Luster: Vitreous to waxy; Crystal structure: Non-foliated granoblastic; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Honey-orange to yellow (due to hematite or goethite staining); Luster: Vitreous to waxy; Crystal structure: Non-foliated granoblastic; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. The rounded shape indicates it has been tumbled in a river or stream bed over thousands of years.
Uses & applications
Used in landscaping, as decorative 'river rock', and occasionally tumbled for lapidary use. Industrial uses include glassmaking if high purity, or as a crushed stone for construction.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caps of ridges and mountains. The orange coloration is usually a surface stain or internal inclusion of iron minerals that oxidized over time.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its sugary, granular texture that looks like fused sand grains. Commonly found in riverbeds and glacial conglomerates.
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