Feldspar is the most abundant mineral group in the Earth’s crust. There are more feldspars (60%) than all the other minerals combined in the outer (13-17) km of the crust1. Feldspars occur in most igneous and metamorphic rocks. They are less common in sedimentary rocks as they tend to break down to clay minerals in the weathering environment. Feldspars are broadly divided into two groups: alkali feldspars and plagioclase feldspars. Common alkali feldspars are orthoclase, microcline, adularia, and sanidine. Plagioclase feldspars are albite, oligoclase, andesine, labradorite, bytownite, and anorthite.
Hover Box Element