During slow cooling the composition of both the host crystal and the lamellae change with temperature as the lamellae increase in size. The width of lamellae depend on the original crystal composition and the cooling rate. Exsolution lamellae are often planar and their orientation is crystallographically controlled.
Exsolution occurs in many common rock forming minerals. Particularly important examples occur in the pyroxenes between Ca-rich and Ca-poor pyroxenes, and in the alkali feldspars between Na-rich and K-rich feldspars.Alkali feldspars exhibiting exsolution are known as perthites. Amphiboles, in particular gedrite, also exhibit exsolution. Iron-nickel metal in meteorites also can undergo exsolution to form widmanstatten texture.ce.