igneous

Pegmatite (White Granite variant)

Pegmatitic Granite (Quartz and Feldspar rich)

Hardness: 6-7 (Mohs scale); Color: White, cream, or light grey with dark accessory minerals; Luster: Vitreous to pearly; Crystal structure: Very coarse-grained phenocrysts; Cleavage: Two directions for feldspar, none for quartz; Specific Gravity: 2.6 - 2.7.

Hardness: 6-7 (Mohs scale)
Color: White, cream, or light grey with dark accessory minerals
Luster: Vitreous to pearly

Identified April 5, 2026More igneous →

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Physical properties

Formation & geological history

Formed during the final stage of a magma's crystallization. Highly fluid, water-rich melts allow for the growth of crystals over 1 cm in size. Often found in batholiths or dikes, and can be billions of years old or from any major mountain-building era.

Uses & applications

A major source of industrial minerals (feldspar, quartz, mica), an ore for rare elements (lithium, tantalum), and high-quality architectural stone. Some pegmatites yield gemstones like tourmaline or beryl.

Geological facts

Pegmatites are famous for holding the largest crystals ever recorded in the world, sometimes reaching lengths of several meters. They are the primary source for most of the world's sheet mica and lithium.

Field identification & locations

Identify in the field by its exceptionally large crystal size compared to average granite. Collectors should look for 'pockets' where well-formed crystals might occur. Found globally in continental basement rocks.

Other igneous specimens

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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