What is the primary component of anorthosite?

Anorthosite is primarily composed of feldspar, specifically plagioclase feldspar, which makes up more than 90% of its mineral composition. This igneous rock is significant for its unique structure and composition, featuring a high percentage of feldspar, making it distinct from other igneous rocks like granite or basalt, which contain higher amounts of quartz or other minerals.

In terms of context, silica, which is a primary constituent of many rocks, is not the defining characteristic of anorthosite, as feldspar plays the dominant role. Quartz is typically found in granitic rocks and does not make up a significant portion of anorthosite. Basalt, on the other hand, is a different type of volcanic rock that consists mainly of pyroxene and plagioclase but does not have the same composition as anorthosite. Therefore, the focus on feldspar as the primary component is what accurately reflects the nature and classification of anorthosite.