Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: June 1, 2025
The cavity within the coated part of the pebble is filled up without vacuity, first, with colourless siliceous crystals; secondly, with fuliginous crystals; and, lastly, with white or colourless calcareous spar. But between the spar and crystals there are many sphericles, seemingly of iron, half sunk into each of these two different substances.
The changes at or near Cape Florida, from the Atlantic coast and its siliceous sand, to the Florida coast and its coral sand, must be curious. You will be free to move from one end of the reef to the other, which will be, say one hundred and fifty miles. Motion to eastward would be slow in the windy season, though favored by the Gulf Stream as the winds are "trade."
It is plain, that our author has imagined to himself an unknown manner of executing his mineral metamorphoses. He sees plainly that the common notion of infiltration will not at all explain the evident confusion of those calcareous and siliceous bodies which appear to him to be metamorphosing into each other.
But this is saying no more in relation to the mineral operations employed upon the siliceous substance, than it would be, in relation to those upon gold, to say that this metal is dissolved by aqua regia.
Nor is it sufficient only to dissolve the siliceous substance which is to be transported; the necessary conditions for the concretion again of the dissolved substances, whatever these may be, are also absolutely required for this operation.
It was held by the former that as gold was not probably existent in nature in any but its metallic form, therefore it had been deposited in its siliceous matrix while in a molten state, and many ingenious arguments were adduced in support of this contention.
The ranges on either side of the glen were generally varieties of gneiss and granite, in many of which feldspar predominated, coarse ferruginous sandstone, and a siliceous rock with mammillary hematite and hornblende. These, and a great mixture of iron ores, composed the first or eastern line of Stanley's Barrier Range.
But the action was hydrothermal, just such as was seen in course of operation in New Zealand a few years ago when, in the Rotomahana district, one could actually see the growing of the marvellous White and Pink Terraces formed by the release of silica from the boiling water exuding from the hot springs, which water, so soon as the heat and pressure were removed, began to deposit its silica very rapidly; while at the Thames Gold-field, in the same country hot, silicated water continuously boiled out of the walls of some of the lodes after the quartz had been removed and re-deposited a siliceous sinter thereon.
Calcareous matter is constantly dissolved by water, when it is exposed to the washing of that fluid; and it is even dissolved out of the most perfect union or combination with siliceous substance, and the most solid composition of an insoluble body, as may be perceived in the decaying of feld-spar.
Section through, from top to bottom: Siliceous sandstone. Shale. 1. Main coal, 6 feet 6 inches, with creeps a, b, c, d. Shale eighteen yards thick. 2. When a bed of coal is worked out, pillars or rectangular masses of coal are left at intervals as props to support the roof, and protect the colliers.
Word Of The Day
Others Looking