Pegmatite is a very course grained plutonic igneous rock. The grain size must be 20mm or more. The appearance of a pegmatite is distinct as the large crystals embedded within the host rock often have a strong contrast in colors and textures.

Pegmatites may contain gemstones such as corundum (ruby and sapphire), tourmalines (such as elbaite and schorl), beryls (such as emerald and aquamarine), and topaz.

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