igneous
Granitic Quartz or Pegmatite
Quartz with Orthoclase Feldspar (SiO2 + KAlSi3O8)
Hardness: 6-7 on Mohs scale; Color: Smoky yellow-brown with salmon-pink inclusions; Luster: Vitreous to greasy; Crystal structure: Hexagonal (Quartz) and Monoclinic (Feldspar); Conchoidal fracture on quartz surfaces.
- Hardness
- 6-7 on Mohs scale
- Color
- Smoky yellow-brown with salmon-pink inclusions
- Luster
- Vitreous to greasy
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Smoky yellow-brown with salmon-pink inclusions; Luster: Vitreous to greasy; Crystal structure: Hexagonal (Quartz) and Monoclinic (Feldspar); Conchoidal fracture on quartz surfaces.
Formation & geological history
Formed from the slow cooling of magma deep within the Earth's crust, typical of intrusive igneous environments like batholiths or pegmatite veins where large minerals have time to solidify.
Uses & applications
Used in construction as crushed stone or landscaping gravel; high-quality quartz is used in electronics and glassmaking; feldspar is used in ceramics and glass.
Geological facts
This specimen shows a mix of quartz (the translucent, glassy parts) and feldspar (the opaque, pinkish-orange parts). This combination is the foundation of most Earth continental crust.
Field identification & locations
Identify in the field by looking for 'glassy' translucent surfaces that don't have parallel edges (quartz) mixed with opaque, blocky crystals that show flat cleavage faces (feldspar). Commonly found in mountainous regions or riverbeds downstream from granitic outcrops.
