albitisation

Albitisation is a geological process that involves the alteration of igneous rocks, particularly granites, into albite-rich rocks. This process is typically associated with the metamorphism of rocks in contact with hydrothermal fluids or during regional metamorphism. Albite is a sodium-rich plagioclase feldspar mineral, and its formation is often linked to the introduction of sodium into the rock system, which can occur through the interaction with saline fluids or the breakdown of other sodium-bearing minerals.

The albitisation process can lead to the formation of albite-rich rocks such as albite granites, albite syenites, and albite-rich pegmatites. These rocks are characterized by their high albite content, which can range from 50% to 90% of the total feldspar content. The remaining feldspar content is typically composed of potassium-rich feldspars such as orthoclase or microcline.

Albitisation can occur over a range of temperatures and pressures, but it is typically associated with low to moderate-grade metamorphism. The process can result in the formation of albite-rich veins or zones within the host rock, as well as the alteration of the entire rock mass. The resulting albite-rich rocks can have important economic implications, as they can be a source of sodium and other valuable minerals.

The study of albitisation is important for understanding the geological history of a region, as well as for identifying potential mineral resources. The process can also provide insights into the behavior of hydrothermal fluids and the role of sodium in geological systems.