igneous

Quartz with Mica inclusion

Silicon Dioxide (SiO2) with Muscovite/Biotite inclusions

Hardness: 7 (Mohs scale); Color: White to translucent with black flaky inclusions; Luster: Vitreous to pearly; Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: White to translucent with black flaky inclusions
Luster: Vitreous to pearly

Identified March 21, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich magma or from hydrothermal veins. Often found in granitic pegmatites. Geological age ranges from Precambrian to Cenozoic depending on the specific deposit site.

Uses & applications

Used primarily as decorative specimens for collectors, in gemstone carvings, or industrially for glassmaking and electronics (if high purity quartz).

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Inclusions like the dark mica seen here are often called 'internal maps' by geologists to determine the mineral's formation history.

Field identification & locations

Identify by its ability to scratch glass and the lack of cleavage. Look for the black, flaky sub-metallic texture of mica. Commonly found in mountainous regions or riverbeds downstream from granitic outcrops.

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Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

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Magnetite (Fe3O4)

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