. Report of the geological exploration of the fortieth parallel . illing of the vein consists usually of an ore-seamwhich is from 2 to 14 inches thick, averaging about 8 inches, and with this isassociated a gangue rock of somewhat varied character. The gangue, appa-rently most intimately associated with the ore, is a mixture of quartz andfeldspar, the latter being sometimes in coarse particles. Sometimes thismaterial is talcose and finely laminated. Gangue of this character almostalways, if not invariably, accompanies the ore, frequently occupying the spacebetween the several seams of pay-mine
. Report of the geological exploration of the fortieth parallel . illing of the vein consists usually of an ore-seamwhich is from 2 to 14 inches thick, averaging about 8 inches, and with this isassociated a gangue rock of somewhat varied character. The gangue, appa-rently most intimately associated with the ore, is a mixture of quartz andfeldspar, the latter being sometimes in coarse particles. Sometimes thismaterial is talcose and finely laminated. Gangue of this character almostalways, if not invariably, accompanies the ore, frequently occupying the spacebetween the several seams of pay-mineral. In other parts of the vein, andoften closely associated with the forcgoiug, the vein-rock appears to be com-posed of quartz, feldspar, and mica, presenting the appearance of true two kinds of gangue rock sometimes occur separately, sometimestogether; in the latter case there is usually a marked difference in theirappearance, hardness, color, and mineral composition, which suggests thatthey are of different age or origin. Plate .XXXV s> a r. bcba _
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