Igneous
Coarse-grained Granite (Quartz and Feldspar dominated)
Granitoid (KAlSi3O8 – NaAlSi3O3 – CaAl2Si2O8 – SiO2)
Hardness: 6-7 on Mohs scale; Color: Pink, reddish-brown, and white/clear crystals; Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse crystals); Cleavage: Perfect on feldspar grains, none on quartz grains; Specific Gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, reddish-brown, and white/clear crystals
- Luster
- Vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, reddish-brown, and white/clear crystals; Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse crystals); Cleavage: Perfect on feldspar grains, none on quartz grains; Specific Gravity: 2.63 to 2.75.
Formation & geological history
Formed by the slow cooling and crystallization of felsic magma deep beneath the Earth's surface (plutonic formation). This specimen likely originated in a continental crust environment where high silica content was present. Geological age can range from billions of years (Precambrian) to more recent tectonic events.
Uses & applications
Used extensively in construction (dimension stone), countertops, monuments, and as crushed stone for road base. Specimens with distinct large crystals are often kept in teaching collections or by amateur mineralogists.
Geological facts
Granite is the most common rock found in the continental crust. The pink/red color in this specific sample is caused by the presence of Potassium Feldspar (Orthoclase), while the translucent/white areas are Quartz grains.
Field identification & locations
Identify in the field by its interlocking 'salt and pepper' or multicrystalline texture and high hardness (it will easily scratch glass). It is commonly found in mountainous regions or shield areas like the Canadian Shield or the Appalachians. Collectors should look for weathered outcrops where individual crystals have been exposed.
