feldspathic

Feldspathic is a geologic and mineralogical term used to describe rocks, soils, or ceramics that are rich in feldspar minerals, especially plagioclase and alkali feldspars (such as orthoclase, microcline, and albite). Feldspar is the most abundant mineral group in the Earth's crust, and feldspathic materials are common in continental crustal rocks. In igneous geology, feldspathic rocks have compositions dominated by feldspar and are typically classified as felsic to intermediate; common examples include granite, granodiorite, rhyolite, and their volcanic equivalents. In sedimentary geology, feldspathic rocks include feldspathic sandstones such as arkose, which contain a substantial proportion of feldspar grains in contrast to quartz arenites.

Weathering of feldspathic rocks tends to produce clay minerals, such as kaolinite or illite, as well as silica. Feldspar grains may weather more quickly than quartz, imparting characteristic textures.

In industrial contexts, feldspar minerals are important fluxes in glassmaking and ceramic production, reducing melting temperatures and improving glaze properties; as a result, feldspathic materials are prized in porcelain clays and ceramic bodies. The term feldspathic is also used to describe soils derived from feldspar-rich rocks and can influence soil fertility and texture.