igneous
Alkali Feldspar Granite
Alkali Feldspar Granite (KAlSi3O8)
Hardness: 6-6.5 Mohs. Color: Salmon pink to reddish-orange with flecks of white. Luster: Vitreous to pearly. Crystal structure: Phaneritic (crystalline). Cleavage: Two directions at 90 degrees. Specific gravity: 2.5-2.7.
- Hardness
- 6-6
- Color
- Salmon pink to reddish-orange with flecks of white
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-6.5 Mohs. Color: Salmon pink to reddish-orange with flecks of white. Luster: Vitreous to pearly. Crystal structure: Phaneritic (crystalline). Cleavage: Two directions at 90 degrees. Specific gravity: 2.5-2.7.
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonic). This cooling allows large crystals to develop. Geological age varies greatly but is common in Precambrian shields and Paleozoic orogens.
Uses & applications
Primarily used as a decorative stone in architecture, countertops, and flooring. It is also crushed for use in road construction and landscaping.
Geological facts
The pink color in this specimen is caused by orthoclase or microcline (potassium feldspar). Granite makes up a large portion of the Earth's continental crust and is exceptionally durable against erosion.
Field identification & locations
Identify in the field by its interlocking crystalline texture and lack of layering (foliation). It is commonly found in mountainous regions or where ancient continental cores are exposed. Look for the distinct salmon-pink hue of the feldspar minerals.
