What is another word for greisen?
Pronunciation: [ɡɹˈa͡ɪzən] (IPA) 
Greisen is a rock type composed mainly of quartz and mica, often found in granite rocks. Synonyms for greisen include granite greisen, quartz-mica greisen, and pegmatite greisen. Granite greisens are typically found in highly evolved granites that have undergone extensive alteration. Quartz-mica greisens are also derived from granite, but they have undergone more extensive alteration, resulting in the formation of minerals like tourmaline and topaz. Pegmatite greisens are formed in pegmatites, which are bodies of rock that consist of large crystals and are often enriched in rare elements. These types of greisens are typically associated with tin and tantalum deposits.
