metamorphic
Feldspar-rich Quartzite
Metamorphic Quartz-Feldspar Aggregate (SiO2 + KAlSi3O8)
Hardness: 6-7 (Mohs scale); Color: Mottled brown, tan, and white; Luster: Vitreous to waxy when wet; Crystal structure: Macro-crystalline to granular; Cleavage: Poor; Specific gravity: ~2.6-2.7
- Hardness
- 6-7 (Mohs scale)
- Color
- Mottled brown, tan, and white
- Luster
- Vitreous to waxy when wet
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Mottled brown, tan, and white; Luster: Vitreous to waxy when wet; Crystal structure: Macro-crystalline to granular; Cleavage: Poor; Specific gravity: ~2.6-2.7
Formation & geological history
Formed from the metamorphism of sandstone rich in feldspar (arkose) under heat and pressure. The specimen shows rounded edges consistent with fluvial (river) transport and weathering. Found in the Alpine-Carpathian transition zone, which fits the 47.7N, 16.5E location (Burgenland/Lower Austria region) where sedimentary and metamorphic units overlap.
Uses & applications
Used primarily as construction aggregate, road base, or in landscaping. Polished versions are used for decorative stone or as aquarium gravel.
Geological facts
The brown coloration is typically due to iron oxide staining (limonite or hematite) within the grain boundaries. Quartzite is one of the most durable and weather-resistant rocks on Earth.
Field identification & locations
Can be identified by its inability to be scratched by a steel knife and its granular texture. It is extremely common in the river beds of central Europe due to the erosion of the Eastern Alps.
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