About Reference Standards

Uses of Cargille Precision Glass Refractive Index Standards

Cargille’s M-1 Reference Set supplements Cargille Refractive Index Liquids by explaining the types of standards available for microscopic identification by refractive index determinations.

The specimens in the M-1 Reference Set were selected for their placement on the refractive index scale and for their accuracy and purity. As many optical glasses as possible were used, and new specimens are constantly being explored for possible inclusion as they contribute to the accuracy or completeness of the collection.

Cargille’s M-7 Reference Set is of particular value to the mineralogist and forensic scientist interested in very accurate refractive index and dispersion measurement using Becke line and a hot stage microscope. Composed of comminuted optical glasses and purified minerals, selected for their optical precision, the set covers the same range of indices of refraction (1.34 to 2.40) and increments (0.01) as Set M-1, but is accompanied by extensive technical data.

Resources for Using Cargille Reference Standards

Becke Line Method

For detailed technical information on using the Becke Line method please see Cargille’s Technical Bulletin RI-T-196 Microscope Techniques: The Becke Line Method.

Measuring Refractive Index of Liquids Using Cargille Reference Standards

Please see also: Measuring Refractive Index of Liquids Using Cargille Precision Solid Refractive Index Standards Reference Sets M-7, M-18 and M-25.

Uses of Comminuted Minerals

Microscopical examination of pure minerals in comminuted form provides insight to many individual characteristics of materials difficult to determine as solids. Some of the many properties which may be ascertained from comminuted materials are: exact determination of refractive indices by the immersion method, separation studies into isotropic and anisotropic groups, extent of birefringence, conoscopic observation of interference figures in particles oriented at random, crystallographic and cleavage studies, pleochroism (when present) in all shades of color, extinction angle with reference to cleavage traces, color observations of finely divided material, microscopic inclusions. Also, comminuted materials have broad applications in spectroscopy; specific gravity determinations and in many microchemical procedures.

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