Lake Champlain Iron Region - No. 2. [Volume: 8, Issue: 6, 1890, pp. 322-331]

328

UNITED STATES ASSOCIATION OF

[VOL. 8,

of Plattsburgh, with which they are connected by the Chateaugay
railroad (3 feet gauge). The two veins of ore strike northeast and
southwest, and dip at high angles to the northwest. The ore has
been opened almost continuously on the main vein for a length of
2500 feet, and in twenty-two slopes. Prof. Smock says: "In the
eastern slopes the depth ranges from 500 to 600 feet, and the ore
is rather soft and coarse 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 feldspar and quartz occur in the ore,
either in thin laminae with the magnetite, or in scattered grains
through the mass. The western slopes are from 1000 to 1100 feet
long, and 650 to 700 feet deep, vertically. The average dip at the
west is 45~ north; at the eastern slopes, it is 70~ northeast. 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
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 finelycrystalline 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 of the shipping ore is shown
by the following analysis:
Per cent.
Peroxide of iron,..... 49.979
Protoxide of iron,....... 22.489
Oxide of manganese,. 0.169
Alumina,......... 1.363
Lime,........... 4.049
Magnesia,...... 1.970
Silica,........... 18.447
Phosphoric acid,. 0.068
Sulphur,........ 0.052
Total,. 98.586
Metallic iron,.. 52.47
Phosphorus,......... 0.029