Circular 127 — Determinative tables of 2Θ_Cu and 2Θ_Fe for minerals of southwestern United States

By C. W. Walker and J. R. Renault, 1972, 102 p.

The conversion of Bragg angle or two-theta (20) to interplanar spacing is a time-consuming step in the routine identification of minerals by X-ray diffraction methods. Furthermore, the derived "d-spacings" do not bear a linear relationship to the diffractometer record and introduce an additibnal error in the interpretation of diffraction spectra. The tables appearing in this publication alleviate these inconveniences in the X-ray identification of inorganic materials. This information is useful to persons working in the mineral industries and sciences.

Selection of minerals included in the tables was made primarily on the basis of species included in Stuart A. Northrop's Minerals of New Mexico (University of New Mexico Press, 1959). The names ankerite, endlichite, jenkinsite, martite, piedmontite, and rossite, however, do not appear in the tables due to inadequate X-ray data, or because they are synonymous with other mineral names. Several species, likely to occur in New Mexico or which are sufficiently important, have been included in the tables even though not reported in Northrop's compilation. Thus, these tables should not be used as an authority on the occurrence of minerals in New Mexico.

G. Y. Chao (Geological Paper 69-2, Carleton Univ., Ottawa, 1969) prepared a similar set of tables; however, the tables published herein are more applicable to mineral studies of materials from the southwestern United States. Tables for iron radiation are also included to facilitate studies of mixtures containing iron-bearing minerals.