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Taylor's way had led him and his party over a deep fresh-water lake, four miles long, which was only surface frozen this lake was full of algae. The gravels below a promising region of limestones rich in garnets were washed for gold, but only magnetite was found.
Hard compact rock of light red color, cut in all directions by narrow veins of quartz, from microscope size to one-half an inch in width. The grains of the constituent minerals, quartz, feldspar and magnetite have an angular brecciated appearance; showing uneven extinction and strong crushing effects.
One of the most interesting and striking investigations made by Edison in this connection is worthy of note, and may be related in his own words: "I felt certain that there must be large bodies of magnetite in the East, which if crushed and concentrated would satisfy the wants of the Eastern furnaces for steel-making.
Magnetite, Titanoferrite, and Iron-pyrites also occur as normal constituents of various igneous rocks, although in very small amount, as also Apatite, or phosphate of lime. The other salts of lime, including its carbonate or calcite, although often met with, are invariably products of secondary chemical action.
The magnetite is somewhat decomposed, the resulting hematite filling the spaces between the quartz grains. 15 Anorthosite Shore of Lake Michikamau. A coarse grained rock of dark gray color, in which labradorite is the chief mineral. Magnetite and Kaolin are present in small quantities.
Basalt is the most fusible of volcanic rocks, owing to the augite and magnetite it contains, so that it spreads out with a very slight slope when highly fused. Trachyte, on the other hand, is the least fusible owing to the presence of orthoclase felspar, or quartz; so that the volcanic domes formed of this material stand at a higher angle from the horizon than those of basaltic cones.
Magnetite seems to have acquired its polarity in the same manner, namely by the earth's induction, when the ore contains a large enough percentage of pure iron. Iron fences invariably exhibit only the polarity by vertical induction; so also small buckets, bells, etc.
The rock has been subjected to strong shearing force, producing a good example of schistose structure. 12 Quartzite Same location as No. 9. A compact rock of light red color, made up of uniformly rounded grains of quartz, and the feldspar with occasional grain of magnetite. A fine siliceous material discolored by iron oxide, acts as a cement between the grains.
When Delaware Bay begins to be whitened with the sails of returning coal-vessels, or lashed with the wheels of steam carriers, bringing in the oxides and magnetite ores of North Carolina and the hematite and other varieties of the extreme South, to mix with the rail-brought ores of interior localities, then Wilmington proposes to be the chosen centre of industry in cast iron.
10 Schistose Limestone Same location as No. 9. A white rock having a peculiar mottled appearance due to the inclusions of decomposing biotite which project from the surrounding mass of calcite. There is some sericite present, also magnetite, resulting from the decomposition of the biotite.
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