igneous
Granite (with Quartz Vein and Biotite)
Granite (Plutonic Igneous Rock)
Hardness: 6-7 on Mohs scale. Color: Speckled salt-and-pepper look with pink/tan orthoclase feldspar, milky translucent quartz, and dark biotite mica specs. Luster: Vitreous to dull. Texture: Phaneritic (medium to coarse-grained) stream-worn pebble with a quartz vein and reflective mica flakes.
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Speckled salt-and-pepper look with pink/tan orthoclase feldspar, milky translucent quartz, and dark biotite mica specs. Luster: Vitreous to dull. Texture: Phaneritic (medium to coarse-grained) stream-worn pebble with a quartz vein and reflective mica flakes.
Formation & geological history
Formed deep within the Earth's crust through the slow crystallization of felsic magma underground over millions of years. Quartz veins form later when silica-rich fluids fill fractures within the cooling pluton.
Uses & applications
Widely used as a construction material, dimensional stone, countertops, paving, and crushed stone for roads. Small rounded river pebbles are collected for landscapes, decorative displays, or educational samples.
Geological facts
Granite makes up a huge portion of Earth's continental crust. The small shiny metallic reflection seen in this specimen is a flake of biotite or muscovite mica, which cleaves into paper-thin, highly reflective sheets.
Field identification & locations
Identify in the field by its speckled phaneritic texture, interlocking crystals of quartz, feldspar, and dark minerals, and its high hardness (scratches glass). Commonly found along riverbeds, glaciated terrains, and mountain ranges globally.
