The Microscopical Characters of Artificial Inorganic Solid Substances: Optical Properties of Artificial Minerals
By Alexander Newton Winchell and Horace Winchell
© 1989, McCrone Research Institute, Inc., Chicago, IL
“The objective here is to emphasize compounds that a chemist might consider relatively ‘pure’ — at least, pure as compared with naturally occurring compounds known as minerals. Descriptions of substances in this book are given in approximately the following order: Chemical formula and name, if any. Crystal symmetry and the dimensions of the unit cell, or the axial ratios if the dimensions are unknown.
Brief data on crystal habit, cleavage, twinning, and such. Hardness, (H, according to Mohs’ scale) and specific gravity (G), and fusibility (F, according to von Kobell’s scale) or melting point in degrees Celcius.
Optical properties, including optic orientation; extinction angles to prominent elongation, cleavages, or crystal faces (for which the orientation of the section must always be specified); principal refractive indices for light of wavelength corresponding to the Fraunhofer line D of sodium, and if possible for other wavelengths; optic sign, optic axial angle (2V), dispersion color, pleochroism, and absorption.” (Winchell, 1989, p. v)