An X-Ray Investigation of the "High"-"Low" Albite Relations

As shown in the accompanying paper by Tuttle and Bowen, two kinds of albite exist. They are distinguished by optical properties and differences in X-ray powder patterns. The generally known "normal" albite (called "low" albite in this paper) is one type, the other (here called "high" albite) can be obtained by heat treatment of "low" albite or by direct synthesis. This investigation deals with some of the "low-high" albite relations. X-ray investigations combined with optical measurements have been carried out. The optical measurements are similar to those reported by Tuttle and Bowen. Structural differences as revealed by the X-ray photographs are discussed. The lattice of "low" albite differs from that of "high" albite in that (010)$$\Lambda$$(100) changes from 90°30' to 88°15' and (010)$$\Lambda$$(001) from 86°20' to 86°0'. This lattice difference is accompanied by changes in intensities of the X-ray reflections. The structural differences, as far as they are expressed as intensity differences of the X-ray reflections, are of the same order of magnitude as the differences in microcline and orthoclase.