metamorphic
Yellow Quartzite Pebble
Quartzite (SiO2 with Iron Oxide staining)
Hardness: 7 on Mohs scale; Color: Yellow-brown due to iron impurities; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); SG: 2.63 - 2.65
- Hardness
- 7 on Mohs scale
- Color
- Yellow-brown due to iron impurities
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Yellow-brown due to iron impurities; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); SG: 2.63 - 2.65
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under extreme heat and pressure. This specimen shows significant rounding from alluvial or glacial transport, likely during the Holocene or Pleistocene.
Uses & applications
Used primarily as decorative landscaping stone, in road construction as aggregate, and sometimes as a minor gemstone or for flintknapping.
Geological facts
Quartzite is so tough that it usually breaks through the quartz grains rather than along the boundaries between them, unlike sandstone. The yellow tint is usually caused by the presence of Geothite or Limonite.
Field identification & locations
Identify in the field by its hardness (will scratch glass easily) and its sugary texture under a hand lens. Commonly found in riverbeds, glacial tills, and coastal regions.
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