metamorphic
Yellow Quartzite
Quartzite (SiO2 with iron oxide impurities)
Mohs hardness: 7. Color: Yellow to tan/orange. Luster: Vitreous to dull. Crystal structure: Hexagonal (microcrystalline). Texture: Granular, sandpaper-like surface but very hard. Cleavage: None, breaks with conchoidal fracture.
- Hardness
- 7
- Color
- Yellow to tan/orange
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Mohs hardness: 7. Color: Yellow to tan/orange. Luster: Vitreous to dull. Crystal structure: Hexagonal (microcrystalline). Texture: Granular, sandpaper-like surface but very hard. Cleavage: None, breaks with conchoidal fracture.
Formation & geological history
Forms through the metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize and fuse together. The yellow color is typically due to the presence of secondary iron oxides like limonite.
Uses & applications
Used as decorative stone in landscaping, as a building material, in road construction, and occasionally for lapidary work or as river stones in residential gardens.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the ridges and peaks of mountain ranges because it weathers more slowly than the surrounding rocks. It was also used by prehistoric humans to make stone tools when flint was unavailable.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its tendency to break through the quartz grains rather than around them (unlike sandstone). Commonly found in ancient mountain belts and riverbeds.
