igneous

Granatic Pegmatite

Pegmatitic Granite

Hardness: 6-7 (Mohs); Color: Pink (feldspar), White/Gray (quartz), Silver-green (mica); Luster: Vitreous to pearly; Crystal structure: Very large interlocking crystals; Cleavage: Good in feldspar and mica areas.

Hardness: 6-7 (Mohs)
Color: Pink (feldspar), White/Gray (quartz), Silver-green (mica)
Luster: Vitreous to pearly

Identified April 4, 2026More igneous →

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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. Typically found in batholiths and mountain-forming regions.

Uses & applications

Used as a source of rare elements (lithium, tantalum), as commercial granite for countertops, and as a source for gemstone-quality minerals like beryl or tourmaline.

Geological facts

Pegmatites are unique because they contain the largest crystals found on Earth; some spodumene crystals in pegmatites have reached lengths of over 40 feet.

Field identification & locations

Identify in the field by the exceptionally large grain size (over 1cm) compared to surrounding rock. Look for the distinct mix of salmon-pink potassium feldspar and glassy quartz.

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