The determination of the orthoclase content of homogenized alkali feldspars using the 2̄01 X-ray method

Abstract
Summary: Forty-three natural alkali feldspars have been homogenized and used to correlatewith wt % K2O. The regression of Or onis Or (wt %) = 465·5(Å)-1877·5, and is comparable to that obtained on an exchanged orthoclase (Wright, 1968). A deviation from the Orville (1963, 1967) determinative line for synthetic sanidine-albite is greatest at the high potassium end of the series. The discrepancy is not caused by failure to homogenize or incomplete disorder. The presence of cations other than potassium and sodium, or cation deficiency, or both cannot be discounted as a cause.