metamorphic
Quartzite (Pink/Red variety)
Quartzite (SiO2 with iron oxide impurities)
Hardness: 7 on Mohs scale; Color: Pink, reddish-purple to light grey; Luster: Vitreous to dull; Crystal structure: Non-foliated, interlocking quartz grains; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Pink, reddish-purple to light grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Pink, reddish-purple to light grey; Luster: Vitreous to dull; Crystal structure: Non-foliated, interlocking quartz grains; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. The pink coloration is typically due to the presence of hematite or other iron oxides during formation. Often dates back to the Proterozoic or Paleozoic eras.
Uses & applications
Used in construction as crushed stone for road heavy-duty ballast, architectural facing stone, and high-quality specimens are used for lapidary work like cabochons or garden decorative stones.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in the landscape, forming prominent ridges. It is often confused with marble, but unlike marble, quartzite will not fizz in contact with weak acid.
Field identification & locations
Identify in the field by its extreme hardness (it will easily scratch glass) and its sugary, crystalline texture. Commonly found in mountainous regions or glacial till. Collectors value smooth, water-worn river cobbles for their aesthetic patterns.
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