metamorphic
Purple Quartzite
Quartzite (SiO2 with iron oxide impurities)
Hardness: 7 on Mohs scale. Color: Pale purple, lavender, pinkish-grey. Luster: Vitreous to sugary/dull when unpolished. Structure: Granoblastic, interlocking quartz grains. Cleavage: None.
- Hardness
- 7 on Mohs scale
- Color
- Pale purple, lavender, pinkish-grey
- Luster
- Vitreous to sugary/dull when unpolished
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Physical properties
Hardness: 7 on Mohs scale. Color: Pale purple, lavender, pinkish-grey. Luster: Vitreous to sugary/dull when unpolished. Structure: Granoblastic, interlocking quartz grains. Cleavage: None.
Formation & geological history
Formed from the regional or contact metamorphism of quartz-rich sandstone under intense heat and pressure, recrystallizing quartz grains. The purple tint is caused by trace inclusions of hematite or manganese.
Uses & applications
Used as decorative stone, construction aggregate, railway ballast, and occasionally for lapidary work and rock tumbling.
Geological facts
Quartzite is so hard and durable that when it fractures, it breaks through the quartz grains rather than along the boundaries between them, unlike sandstone.
Field identification & locations
Identified by its extreme hardness (scratches glass easily), lack of reaction to acid, and sugary appearance on fresh surfaces. Commonly found in glacial drift, riverbeds, and ancient mountain belts.
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