The accuracy of cell dimensions determined by Cohen's method of least squares and the systematic indexing of powder data

A procedure is described for obtaining the standard deviations in cell dimensions derived front powder patterns by Cohen's method of least squares. The analysis applies to any crystal system and the error in the volume of the cell is evaluated. The method is particularly suited to the study of minerals where isomorphous replacements give rise to small changes in lattice parameters. As an example, the cell dimensions and their errors are obtained for an iron-rich actinolite asbestos and the powder pattern is indexed.