metamorphic
Yellow Quartzite
Metamorphosed Quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Yellow to honey-gold due to iron oxide inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Yellow to honey-gold due to iron oxide inclusions
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Yellow to honey-gold due to iron oxide inclusions; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, causing the original quartz grains to recrystallize and fuse into a dense, hard rock. The yellow coloration typically results from the presence of limonite or goethite.
Uses & applications
Used primarily as decorative stone, in construction as crushed stone for road beds or railroad ballast, and occasionally in jewelry as tumbled stones or cabochons. It is highly valued in landscaping.
Geological facts
Quartzite is so hard that it will scratch glass and steel. In some ancient cultures, it was used to create tools much like flint, though it is more difficult to flake precisely.
Field identification & locations
Identify in the field by its extreme hardness and grainy, sugary texture that resembles sandstone but cannot be rubbed off. Found globally in mountainous regions where tectonic activity has occurred.
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