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Updated: June 1, 2025
Now, when the siliceous substance, which is the insoluble part, shall be supposed resisting every effort of the elements towards its dissolution, those compound masses upon the surface of the earth, however endued with hardness and solidity, are gradually impaired by the dissolution of some of their constituent parts, and by the separation of others which are thus exposed to the ablution of water.
The commonly accepted theory, however, is that the alluvial matter of our drifts has been ground out of the solid siliceous lodes by glacial and fluvial action, and that the auriferous leads have been formed by the natural sluicing operations of former streams. To this, however, there are several insuperable objections.
It is in the solid parts of those strata, perfectly disconnected from the veins, that there are frequent cavities curiously lined with crystals of different sorts, generally calcareous, sometimes containing also those that are siliceous, and often accompanied with pyrites.
We may believe that the same molten mass which supplies this acidic lava in surface flows solidifies as granite deep below ground in the volcanic reservoir. SYENITE, composed of feldspar and mica, has consolidated from a less siliceous mixture than has granite.
In the territory of Nebraska, on the Upper Missouri, near the Platte River, latitude 42 degrees N., a tertiary formation occurs, consisting of white limestone, marls, and siliceous clay, described by Dr. Among these, Dr. Leidy describes a gigantic quadruped, called by him Titanotherium, nearly allied to the Palaeotherium, but larger than any of the species found in the Paris gypsum.
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.
Siliceous matter, physically speaking, is not soluble in water; that is to say, in no manner of way have we been enabled to learn, that water has the power of dissolving this matter.
A numerous series of minerals from Russia, such as red chromate of lead, white carbonate of lead, green phosphate of lead; native copper, green and blue carbonate of copper; gold ore from Berezof; iron ore, granitical rocks, fossil shells, in good preservation, from the banks of the Moscorika, and others in the siliceous state, jaspers, crystals of quartz, beril, &c.
This siliceous substance, viewed in one direction, or longitudinally, may be considered as columnar, prismatical, or continued in lines running nearly parallel. These columnar bodies of quartz are beautifully impressed with a figure on the sides, where they are in contact with the spar.
Ehrenberg suggests that it is composed of the siliceous coverings of a portion of the microscopic creatures, whose shells he has in other instances detected in their original condition.
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