igneous

Granitic Pegmatite with Schorl

Granitic Pegmatite (NaAlSi3O8, KAlSi3O8, SiO2) with Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)

Hardness: 6-7.5 (Mohs scale), Color: White/creamy matrix with black tourmaline inclusions, Luster: Vitreous to pearly, Crystal structure: Coarse-grained/Trigonal (Schorl), Cleavage: Poor, Specific Gravity: 2.6-3.1

Hardness: 6-7

Identified March 4, 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 during the final stage of magma crystallization where high water content allows for the growth of exceptionally large crystals. These are typically associated with continental crust and range from Precambrian to Cenozoic geological ages.

Uses & applications

Primary source of industrial minerals (feldspar, quartz, mica), lithium ores, and gemstones. Schorl is used as a collector specimen and occasionally for industrial boron.

Geological facts

Pegmatite crystals can grow to be meters long. Schorl (black tourmaline) is the most common variety of tourmaline and was historically used in the 1700s to pull ash from pipes due to its pyroelectric properties.

Field identification & locations

Identify by the large grain size and the presence of triangular/hexagonal black Schorl crystals. Common in mountain ranges and volcanic shields like Brazil, Namibia, and California. Collectors look for well-defined crystal shapes.

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

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral