An X-ray diffraction pattern of beryl has been indexed and the observed reflections agree with the space group P/6mcc. Chemical analysis of 3 beryl crystals and 12 pegmatitic and aplitic rocks are reported. The chemical, physical, and optical properties of yellow and green beryl from Birch Portage are correlated, and compared with previously published data. This leads to the conclusion that the coloration may be associated with R 2 O components. If these components occupy structural positions, the lattice may be expanded in the direction of c, and if they reside in the open channels of beryl, the lattice may be expanded in the direction of a. The terms "C' type and "A' type beryl are proposed. Birch Portage beryl falls in the latter category.

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