Potassic

Potassic is an adjective relating to potassium, the chemical element with symbol K. In science and industry, potassic describes materials or systems that contain notable amounts of potassium, or that are enriched in potassium relative to other alkaline earth or alkali metals. The term derives from potash, historically derived from wood ashes and used as a source of potassium.

In geology and petrology, potassic denotes rocks and magmas with higher potassium content, typically expressed as K2O, compared with sodium or calcium. Potassic rocks are common in continental crust and include granites, granodiorites, and certain rhyolites. They are contrasted with sodic or calc-alkaline rocks, and with ultrapotassic varieties that have especially high potassium relative to magnesium and iron. The potassic signature can reflect differentiation processes, such as fractional crystallization or subduction-related metasomatism, that concentrate potassium-bearing minerals.

In mineralogy, potassic pertains to minerals rich in potassium. Prominent potassic minerals include potassium feldspars—orthoclase, microcline, and sanidine—and the micas biotite and muscovite. Some other minerals in certain rock types may also be described as potassic when they contribute significant potassium to the mineral assemblage.

In agriculture and soil science, potassic refers to potassium availability and management in soils. Potassium is an essential macronutrient for plant growth, supplied through potassic fertilizers such as potassium chloride (KCl) and potassium sulfate (K2SO4). Potassic fertility is important for crop yield, stress tolerance, and overall plant health.