metamorphic
Orange Quartzite (or Iron-Stained Quartz)
Silicon Dioxide (SiO2) with Iron Oxide impurities (Fe2O3)
Hardness: 7 (Mohs scale); Color: Pale yellow to deep orange/brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65.
- Hardness
- 7 (Mohs scale)
- Color
- Pale yellow to deep orange/brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Pale yellow to deep orange/brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65.
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone, where heat and pressure recrystallize sand grains into a dense, interlocking matrix. The orange coloration is primarily due to the infiltration of iron oxide (limonite or hematite) during or after formation.
Uses & applications
Used widely in construction as crushed stone or decorative landscaping. Higher-grade specimens are used as garden stones, paperweights, or tumbled into 'spirit stones' for metaphysical collecting.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock, often forming the tops of ridges and mountains. A quick field test is that it will scratch glass easily, whereas similar-looking calcite will not.
Field identification & locations
Identify by its 'sugary' texture on fresh breaks and the inability to scratch it with a steel knife. It is commonly found in riverbeds, glacial deposits, and mountain ranges globally. Collectors should look for vibrant, consistent orange hues and translucent edges.
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