The Adirondack Region — Magnetic Iron Ores. 41 



the State prison supply of forge ore, before the opening of the mine 

 on the State property. They have since been idle. 



CHATEAUGAY MINES, town of Dannemora, Clinton county. 

 ■ — These mines are situated on the north slope of Lyon Mountain, 

 which gives name to the railway station at the mines. They are 

 34 miles west of Plattsburgh, and are reached by the Chateaugay 

 railroad. There are two veins of ore, whose course is north-east and 

 south-west, and whose dip is, at high angles, to the north-west. The 

 ore has been opened almost continuously on the main vein for a 

 length of 2,500 feet, and in twenty-two slopes. The principal work- 

 ing slopes are numbers 16, 15 and 14 at the north-east, and near the 

 separating works, and at the western end of the line, slopes Nos. 

 7, 6, 5, 4, 3, the New or Hall shaft, No. 1, and the Cannon shaft, 

 on the back or Burden vein. In the eastern slopes the depth ranges 

 from 500 to 600 feet, and the ore is rather softer and coarser-grained. 

 A notable feature of the range is the uniformity in the wall rocks, 

 which carry some magnetite in the coarse-crystalline aggregate of 

 orthoclase, vitreous quartz and hornblende. More or less feld- 

 spar and quartz occur in the ore, either in thin laminae with the 

 magnetite or in scattered grains through the mass. The lean ore of 

 the vein between slopes Nos. 14 and 7 is not now mined. The west- 

 ern slopes are from 1,000 to 1,100 feet long and 650 to 700 feet deep, 

 vertically. The strike near slope No. 4 becomes west, and the average 

 dip at the west,, is 45° north ; at the eastern slopes, it is 70° north-east. 

 A breadth of 20 feet of ore is won in the western slopes, leaving lean 

 ore in the hanging and foot walls. In consequence of rolls in the 

 walls the slopes are not at uniform angles of descent, and the tracks 

 have to follow the undulations of the foot wall. Trap dikes traverse 

 the ore, crossing it in sheets which are as much as 20 feet thick in 

 some cases, and, in the western slopes, dipping steeply southward. 

 Wherever encountered they are left as pillars to hold up the roof. 

 Near slopes Nos. 14 and 16 they strike transversely across the vein 

 and are vertical.* The ore at the western slopes is rather tine-crys- 

 talline and harder than that at the east, although in breaking it down 

 there is much fine ore. All of the ore is suitable for Bessemer, and 

 the average composition is shown by the following analysis : f 



* There was no opportunity when at the mines to note carefully the mode of occur- 

 ence and collect specimens of these rocks for study. 



f Communicated by Mi-. A. L. Inman, of Plattsburgh, general manager of the 

 Chateaugay Ore and Iron Company. 



