An Expedition to Mount St. Elias, AlaskaRussell, Israel C. (Cook)
History
An Expedition to Mount St. Elias, Alaska
Russell, Israel C. (Cook)
Alaska -- Description and travel; Saint Elias, Mount (Alaska and Yukon)
Macroscopically, the sand has the appearance of ordinary finely
comminuted beach material; but it differs in the uniformity of the
size of its particles from beach sand from Fort Monroe and Sullivan
island, South Carolina, with which it was compared. Its mineralogic
constituents greatly surpass in variety those of the sands referred
to, but are markedly similar to those of gold-bearing sand from New
Zealand. At least twelve minerals are present, with an unusual
predominance of one, as will be noted later. Through the mixture of
white, green, and black grains, a dull greenish-black color is given
to the mass. The roundness of fragments is such as usually results
from water action, but it is less than that which results from
transportation by wind.
When put into a heavy liquid (Thoulet solution of a density of 3.1) in
order to determine the specific gravity of the constituents, it was
found that the sand is made up largely of the heavier materials, for
the amount that floated was trifling compared with that which quickly
sank. Even the abundant quartz was largely carried down by the
weightier ingredients bound up within it, and only a few water-clear
fragments were left behind. This would seem to suggest that the
lighter minerals are lacking in the neighboring rocks, or else have
been carried to greater distances by the sorting power of the water.
Among the minerals recognized, gold is the most important, though
relatively not abundant. It occurs in flakes or flattened grains from
a quarter to a half of a millimeter in size. The particles are
sufficiently numerous to be readily selected from their associates by
the aid of "panning" and a hand lens of good magnifying power, and if
distributed throughout the beach as plentifully as in the sample
would, under favorable conditions, pay for working. The flakes in
their rounded character show the effect of the agency which separated
them from their matrix; a separation so complete that no rock is found
adhering to the grains.
{197} Magnetite is present in great abundance and in a finely divided
state, the largest grains not exceeding a millimeter in length. It
forms by weight alone 15 or 20 per cent. of the entire mass, and when
the latter is sifted through a sieve of a hundred meshes to the inch
it constitutes 44 per cent. of this fine material. Crystallographic
faces are rare, and though often marred, still octahedrons (111, 1) of
considerable perfection are found.
Garnet occurs in such profusion that a pink tint is given to a mass of
selected grains of uniform size, and its predominance may be
considered the chief physical characteristic of the sand.
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