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 May 17, 2026More igneous →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

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.

Other igneous specimens

See all

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

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

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral