metamorphic
Yellow Quartzite (Iron-stained Quartz)
Silicon Dioxide (SiO2) with iron oxide staining
Hardness: 7 (Mohs scale). Color: Translucent golden-yellow to honey-brown. Luster: Vitreous to waxy when weathered. Crystal structure: Trigonal/Hexagonal (microcrystalline in this form). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.
- Hardness
- 7 (Mohs scale)
- Color
- Translucent golden-yellow to honey-brown
- Luster
- Vitreous to waxy when weathered
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Physical properties
Hardness: 7 (Mohs scale). Color: Translucent golden-yellow to honey-brown. Luster: Vitreous to waxy when weathered. Crystal structure: Trigonal/Hexagonal (microcrystalline in this form). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. The yellow coloration is typically a secondary iron-oxide stain (limonite or goethite) that has permeated the grain boundaries of the stone over geological time.
Uses & applications
Used primarily as decorative landscaping stone, in aggregate for construction, and as an ornamental stone for lapidary work such as tumbling and cabochon cutting.
Geological facts
Quartzite is frequently harder than the steel of a pocketknife. It is so durable that it often remains as pebbles in riverbeds long after softer rocks have eroded away. The staining suggests this piece spent significant time in an oxygen-rich, moisture-heavy environment.
Field identification & locations
Identify in the field by its inability to be scratched by steel and its grainy, 'sugary' texture on fresh breaks. It is commonly found in glacial till, riverbeds, and mountainous regions like the Appalachians or the Rockies.
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