Granite

granite, a coarse-grained, pale-coloured igneous rock of plutonic origin (see geology). Feldspars are the dominant constituent, with lesser amounts of quartz together with minerals such as mica and amphibole. The feldspars are rich in potassium, the chief mineral nutrient for vines and an indirect influence on wine flavour, although typically only a small proportion is actually available to the vine. Granitic soils tend to have low fertility, and because the quartz grains resist weathering, such soils are sandy and well-drained. They are widespread and are favoured for viticulture although they tend to be acid. Examples include dão and parts of sardinia, the northern rhône, beaujolais, as well as the Granite Belt of queensland and parts of South Africa’s Western Cape, coastal chile, and California’s Sierra Foothills east of the central valley.