metamorphic
Yellow Quartzite (Orange Quartzite)
Silicon Dioxide (SiO2) with iron oxide staining
Hardness: 7 (Mohs scale); Color: Yellow to orange; Luster: Vitreous to greasy; Crystal Structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63 - 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Yellow to orange
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 (Mohs scale); Color: Yellow to orange; Luster: Vitreous to greasy; Crystal Structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63 - 2.65
Formation & geological history
Formed when quartz-rich sandstone is subjected to intense heat and pressure (metamorphism). The yellow/orange tint is usually caused by the presence of iron oxide (limonite or hematite) during or after the metamorphic process.
Uses & applications
Used in landscaping, construction for decorative stone/countertops, and sometimes as a minor gemstone or in 'healing crystal' collections.
Geological facts
Quartzite is so tough that it often outlasts the mountain ranges that contain it. It typically breaks across the quartz grains rather than around them, distinguishing it from sandstone.
Field identification & locations
Identify by its ability to scratch glass easily and its sugary/granular crystalline appearance. Found globally where ancient mountain belts have undergone metamorphism, such as the Appalachian Mountains or the Alps.
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