metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Gray, white, and rusty orange (from iron staining); Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None/Conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Color
- Gray, white, and rusty orange (from iron staining)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Gray, white, and rusty orange (from iron staining); Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None/Conchoidal fracture.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specific specimen has been further shaped into a rounded pebble by water erosion in a river or coastal environment.
Uses & applications
Used in construction as crushed stone or ballast, in high-end glass manufacturing, and as decorative landscaping stones or polishable tumbling material for collectors.
Geological facts
Quartzite is so tough that it often outlasts the mountains it was formed in, becoming the primary component of river gravel. The orange staining on this piece is likely caused by limonite or hematite (iron oxides) leaching into the grain boundaries.
Field identification & locations
Identify in the field by its extreme hardness (it will easily scratch glass) and lack of visible pores compared to sandstone. Commonly found in glacial deposits and riverbeds. Collector tip: wet the stone to see the internal patterns more clearly.
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