Abstract

In 1892 or 1893 a small lot of calcite crystals of unusual form was collected by Dr. A. E. Foote at Guanajuato, Mexico. There were less than fifty of these crystals and because they were so few and so peculiar in development it may be safely assumed that they all came from one cavity or pocket. In outward appearance these crystals are seemingly oblong prisms, terminating in curved faces which come to a rather sharp point. If it were not evident at once that the mineral is calcite, it could easily be mistaken for a monoclinic substance, elongated parallel to the a axis, with a vertical plane and a twofold axis of symmetry. This oblong prism is bounded by two faces which are not smooth planes but are composed of many slightly curved, bright surfaces which give these faces a somewhat mottled appearance, and by two other faces which are invariably narrower and consist entirely of striations which run in the long direction of the crystal.

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