Igneous

Granitic Pegmatite

Pegmatite (Quartz: SiO2, Feldspar: KAlSi3O8, Mica: KAl2(AlSi3O10)(OH)2)

Hardness: 6-7 (Mohs scale); Color: White, cream, tan with dark inclusions; Luster: Vitreous to pearly; Structure: Phaneritic (very large crystals); Cleavage: Perfect in feldspar and mica constituents.

Hardness: 6-7 (Mohs scale)
Color: White, cream, tan with dark inclusions
Luster: Vitreous to pearly

Identified March 25, 2026More igneous →

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Physical properties

Formation & geological history

Formed during the final stage of a magma's crystallization. Highly water-rich magma allows for rapid ion migration, resulting in exceptionally large crystals. Most common in Precambrian and Paleozoic terrains.

Uses & applications

Source of industrial minerals like quartz and feldspar, or rare metals like lithium and niobium. Decorative stone for landscaping or architectural facades.

Geological facts

Pegmatites are known as the 'nature's giant crystal factory.' Individual crystals in some pegmatite deposits have been known to reach over 10 meters in length.

Field identification & locations

Identify by exceptionally large crystal grains (over 1 cm) compared to standard granite. Often found in mountainous regions or shield areas. Collectors look for specific accessory minerals like tourmaline or beryl within the matrix.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

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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