- 2066 Jestha (old course) · 4 marks
Short note: Quartzite
Short answer
Quartzite is a hard non-foliated metamorphic rock from recrystallized quartz sandstone, over 90% quartz, granoblastic texture. Very hard (Mohs 7), specific gravity 2.65, strength 150-300 MPa, resists weathering. Used as aggregate, ballast, riprap; found in Himalayan Nepal.
Write a short note on quartzite.
Quartzite is a hard, non-foliated metamorphic rock formed by recrystallisation of quartz sandstone under heat and pressure (contact or regional metamorphism).
- Texture and structure: granoblastic texture, with quartz grains fused into an interlocking mosaic; massive; relict bedding may remain.
- Composition: over 90 % quartz, with small amounts of mica, feldspar and iron oxides.
- Properties: colour white, grey, pink or brown; very hard (Mohs 7); specific gravity 2.65; compressive strength 150 - 300 MPa; very low porosity; fractures across grains (conchoidal); resists weathering and chemicals.
- Engineering uses: road metal, concrete aggregate, railway ballast, riprap, and a good foundation rock for dams and bridges. It is hard to excavate and dress and is generally jointed, so joints control seepage and stability.
- Occurrence: found in the Lesser and Higher Himalaya of Nepal, such as in the Nawakot Complex.
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