igneous
Quartz with Mica inclusions (Pegmatite)
Silicon Dioxide (SiO2) with Muscovite/Biotite inclusions
Hardness: 7 (Quartz) to 2.5 (Mica); Color: Tan, white, and smoky grey with black/dark green flaky patches; Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal; Cleavage: None (Quartz) to Perfect Basal (Mica).
- Hardness
- 7 (Quartz) to 2
- Luster
- Vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 7 (Quartz) to 2.5 (Mica); Color: Tan, white, and smoky grey with black/dark green flaky patches; Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal; Cleavage: None (Quartz) to Perfect Basal (Mica).
Formation & geological history
Formed from the slow cooling of magma in intrusive igneous bodies known as pegmatites, which allow for the growth of large, distinct mineral crystals often towards the end of crystallization stages.
Uses & applications
Primarily used as a mineral specimen for collectors or in construction as crushed stone. Certain high-quality pegmatite minerals are used in electronics or as gemstones.
Geological facts
Pegmatites are famous for hosting the largest individual crystals ever found on Earth. The dark inclusion seen here is likely a book of mica or a pocket of schorl tourmaline.
Field identification & locations
Identify by looking for the glassy look of quartz mixed with coarse, flaky dark minerals. Commonly found in mountainous regions with exposed granite basements.
