igneous
Granitic Quartz with Feldspar
Granite (composed primarily of SiO2 and KAlSi3O8)
Hardness: 6-7 (Mohs); Color: Grayish-white translucent (quartz) with fleshy-pink/orange inclusions (feldspar); Luster: Vitreous to greasy; Crystal Structure: Trigonal/Monoclinic; No cleavage in quartz, two directions in feldspar.
- Hardness
- 6-7 (Mohs)
- Luster
- Vitreous to greasy
Identified More igneous →
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Physical properties
Hardness: 6-7 (Mohs); Color: Grayish-white translucent (quartz) with fleshy-pink/orange inclusions (feldspar); Luster: Vitreous to greasy; Crystal Structure: Trigonal/Monoclinic; No cleavage in quartz, two directions in feldspar.
Formation & geological history
Formed from the slow cooling of silica-rich magma beneath the Earth's surface (intrusive). This specimen likely originated from a weathered granitic pluton or pegmatite, subsequently rounded by water action.
Uses & applications
Used in construction as a sturdy building material, as a component in crushed stone, and as a low-cost specimen for elementary geology educational kits.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. When granite wears down, the more durable quartz crystals often end up as the sand seen on the beach surrounding this rock.
Field identification & locations
Identify in the field by its hardness (will scratch glass), translucent gray appearance, and the presence of small, opaque, colored crystals embedded within a crystalline matrix. Found globally in continental basement rocks.
