99 



range from 40 to 80 degrees and as a rule are well over 50 

 degrees. 



Ore shoots — The ore shoots are composite in character 

 and consist of widely parallel bands, lenses and masses of 

 galena and zinc blende alternating with siderite and to a 

 less extent with quartz and calcite. As a rule the high grade 

 ore favours the hanging wall side of the vein, though this 

 is not invariably so. The shoots also favour the carbonace- 

 ous slates rather than the quartzites, porphyry stocks or 

 dykes, but the reverse again holds in a few instances. 

 Another favourable factor in the formation of shoots is 

 the cross fissures which pass across the vein from either the 

 foot or hanging wall side. These appear to have formed 

 accessible channels for the metal bearing solutions. The 

 shoots vary in length from 15 or 20 feet (4-5 or 6 m.) to 

 400 feet (122 m.) or over, and in width from a few inches 

 (cm) to 40 feet (12 m.). 



The vertical component varies from 10 feet (3 m.) or 

 so to 500 and 600 feet (152 to 182 m.) in the larger bodies. 

 In many cases with, however, numerous exceptions, the 

 shoot bears a relation to the topography of the country 

 and pitches out of the hill. With depth the ore gets 

 poorer and passes into slightly mineralized gangue and 

 crushed rock. 



Mineral composition — The chief metallic minerals 

 are galena and zinc blende. With freibergite as the im- 

 portant silver bearing ore, ruby and native silver and 

 argentite are found in many of the deposits developed 

 along fractures in the more massive ore. Chalcopyrite 

 and pyrite are almost invariably present, the former in 

 small amount, the latter in increasing quantity as the lead 

 content diminishes. The zone of weathering is very 

 shallow but originally contained carbonates of lead, zinc 

 and copper and in one instance linarite, a sulphate of 

 lead and copper. 



The gangue is composed of siderite, calcite and quartz 

 in varying proportions, the quartz content usually increas- 

 ing with depth. 



At present the metallic contents of the ores mined 

 range from 7 per cent of lead and 20 ounces of silver to 

 the ton to one carrying from 50 to 75 per cent of lead and 

 from 80 to 1 75 ounces of silver to the ton. In some mines 

 there is a little gold which ranges in value from $1.00 to 

 $7.00 to the ton. 

 36425— 7| 



