. Bulletin - United States National Museum. Science. 302 BULLETIN 131, UNITED STATES NATIONAL MUSEUM. of all edges, the solvent action having been greatest at the ends of the trigonal axes where uneven faces have been produced. Shallow rounded grooves replace the edges between (101) and (211) and a rounding of the angles at the ends of the axes gives, in some cases, an approximation to a cubic face. The etch facets would give no measurable reflections, but their position shows that they are in part trisoctahedrons and in part hexoctahedrons. The faces of both (101) and (211) still retain a bri
. Bulletin - United States National Museum. Science. 302 BULLETIN 131, UNITED STATES NATIONAL MUSEUM. of all edges, the solvent action having been greatest at the ends of the trigonal axes where uneven faces have been produced. Shallow rounded grooves replace the edges between (101) and (211) and a rounding of the angles at the ends of the axes gives, in some cases, an approximation to a cubic face. The etch facets would give no measurable reflections, but their position shows that they are in part trisoctahedrons and in part hexoctahedrons. The faces of both (101) and (211) still retain a brilliant luster, but the former are marked by beautifully symmetrical and sharp etch pits of rhombo- hedral outline, their edges parallel to the dodecahedral edges of the crystal. The faces of (211) are grooved quite deeply parallel to the same edges. The garnets sometimes reach large size. Livingston and Laney u found a portion of a well-formed crystal IS cm. in diameter on the dump of the Arkansaw mine. A number of specimens from this region which have been examined by the writer are described as follows: A specimen from the Peacock claim consists of fine large dark-brown crys- tals up to 2 cm. in diameter embedded in quartz. These are dodecahedrons modified by narrow faces of the trapezohedron. They are asso- ciated with a little hematite and bornite. When broken out these crystals leave perfect molds in the quartz. Although firm and lustrous on the outside, these crystals, when broken, are found to be porous inside with the pores partly filled with chrysocolla. Under the microscope the garnet is transparent, isotropic, and devoid of notable zoning with an index of refraction above , estimated at They are thus midway between grossularite and andradite in composition. A specimen labeled "North drift, railroad tunnel," consists of dense massive, fine-grained pure garnet of brown color and greasy luster. It shows no suggestion of crystals, nor is there any oth
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