igneous
Garnetiferous Pegmatite
Pegmatite with Almandine Garnet and Muscovite
Hardness: 6.5-7.5 (garnets) 6 (feldspar); Color: White to grey matrix with red/pink garnet inclusions; Luster: Vitreous to pearly; Crystal structure: Course-grained igneous; Cleavage: Perfect in mica, poor in garnet.
- Hardness
- 6
- Color
- White to grey matrix with red/pink garnet inclusions
- Luster
- Vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 6.5-7.5 (garnets) 6 (feldspar); Color: White to grey matrix with red/pink garnet inclusions; Luster: Vitreous to pearly; Crystal structure: Course-grained igneous; Cleavage: Perfect in mica, poor in garnet.
Formation & geological history
Formed during the final stages of a magma's crystallization, usually in high-water content environments that allow for very large crystal growth. Typical of continental crust and orogenic belts.
Uses & applications
Used as a source of rare minerals, industrial abrasives (garnet), and sometimes as decorative stone or countertop material. High-quality garnets are used in jewelry.
Geological facts
Pegmatites are famous for containing the largest crystals of any rock type. The red spots are likely almandine garnets, which are common in metamorphic and igneous rocks.
Field identification & locations
Identify by looking for unusually large mineral grains (over 1cm) and the presence of deep red, dodecahedral garnet crystals. Common in pegmatite veins globally, such as in the Northeast US or Brazil.
