igneous
Granite Quartz Blend (Pegmatite or Quartz-rich Granite)
Igneous rock composed primarily of SiO2 (Quartz) with KAlSi3O8 (Feldspar) and (K,Fe,Mg)3(Al,Si4O10)(OH)2 (Biotite)
Hardness: 6-7 (Mohs scale); Color: Tans, pinks, and grays with dark speckles; Luster: Vitreous to dull; Crystal Structure: Phaneritic (visible crystals); Cleavage: None in quartz sections, good in feldspar.
- Hardness
- 6-7 (Mohs scale)
- Color
- Tans, pinks, and grays with dark speckles
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Tans, pinks, and grays with dark speckles; Luster: Vitreous to dull; Crystal Structure: Phaneritic (visible crystals); Cleavage: None in quartz sections, good in feldspar.
Formation & geological history
Formed from the slow cooling of magma deep beneath the Earth's surface. This process allows large crystals to grow, typical of intrusive igneous basement rocks often billions of years old.
Uses & applications
Used primarily as construction aggregate, decorative stone, and in memorials. Large slabs are used for countertops.
Geological facts
Granite makes up a large part of the Earth's continental crust. The pink/tan hue in this specimen suggests a high concentration of potassium feldspar (orthoclase).
Field identification & locations
Identify by its interlocking crystalline texture and lack of layering. It is common in mountain ranges and glacial till across North America and Europe.
