. Bulletin . urium ^Mine. (?, quartz; F, feldspar; .1. lian<rin<r wall schist; C, foot-wall schist; B, bed of light-colored schist. quartzite, for the latter are seldom lenticular in shape, frequently the bedding of the enclosing rock, and are varialjle in their strikeand dip. The lenses forming the Middle vein are separated in jilaccs by adistance of several feet, and the veinlets connecting them may pinch toalmost notliing so that only a faint line remains, but it can usually be dis-tinguished without difficulty. In the partly decomposed schists near the 166 GEOLOGY OF THE G
. Bulletin . urium ^Mine. (?, quartz; F, feldspar; .1. lian<rin<r wall schist; C, foot-wall schist; B, bed of light-colored schist. quartzite, for the latter are seldom lenticular in shape, frequently the bedding of the enclosing rock, and are varialjle in their strikeand dip. The lenses forming the Middle vein are separated in jilaccs by adistance of several feet, and the veinlets connecting them may pinch toalmost notliing so that only a faint line remains, but it can usually be dis-tinguished without difficulty. In the partly decomposed schists near the 166 GEOLOGY OF THE GOLD BELT IX THE JAMES EIVEIl BASIN. surface this line is marked by the dark stain of oxides of iron, probablyfrom the alteration of pyrite; and when the soft material is broken awaya little coarse grit, due to the presence of quartz, can be detected on theline. Feldspar is an important constituent of this vein, but in the open-ings that are now accessible it is completely altered to kaolin. The kaolin ^N. V/.. Fig. 14.—Vertical section of middle vein at the Tellurium Mine, showing large lenscomposed of smaller lenses. occurs in small angular shapes distributed throughout the quartz, but ismostly found along the border portion of the lenses, and especially atpoints where they narrow and pinch out. (See fig. 13.) Some of thesmaller lenses 2 or 3 inches in length are composed entirely of kaolin. Inplaces the larger lenses are made up of a number of smaller ones as shown THE GOLD MIXES OF THE DISTRICT. 16 in fio- 14, and where this occurs there is occasionally a little in-cluded between the component lenses. At one point the vein is cut by avertical fault which displaces the vein about 2 feet. (See hg. lo.) N. E.
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