A large group of minerals that is found in a wide area of the earth, but only a few of its members are suitable for gemstones.Feldspars are divided into several series:orthoclase (embracing moonstone and adularia) and microcline (embracing amazonstone)plagioclase (embracing sunstone, aventurine, feldspar, labradorite, and peristerite)celsian; each with several intermediate seriesThe group has also been called 'feldspath' but now is generally called 'feldspar'. The names of varieties refer to the nature of the Cleavage ('clase', derived from the Greek klasis, cleaving), witha prefix denoting the direction or nature of the cleavage.