Greisenized

Greisenized refers to the process or condition resulting from greisen formation, a type of mineral alteration associated with granitic and tin-ore deposits. Greisen is a highly altered zone of granite or similar intrusive rocks, characterized by their fine-grained, silicified, and often quartz-rich composition. The term "greisenized" describes rocks or mineral assemblages that have undergone this specific alteration, typically involving extensive silicification, leaching of alkali and alkaline earth elements, and mineralogical changes.

The process of greisenization occurs when granitic rocks are hydrothermally altered by mineral-rich fluids associated with mineralization events, especially in tin and tungsten deposits. These fluids replace original minerals with quartz, muscovite, topaz, and other secondary minerals, leading to the formation of greisen. The alteration zone often appears as a zone of increased silicification and mineral enrichment surrounding ore bodies.

Greisenization is significant in economic geology because it often indicates proximity to mineral deposits, particularly tin, tungsten, and molybdenum. The resulting greisen rocks are often mined for residual ore minerals or for the secondary minerals that formed during alteration.

In summary, "greisenized" describes rocks that have been extensively altered to a greisen composition through hydrothermal processes associated with mineralization, serving as an important indicator of mineral deposits in geological exploration.