Common Minerals and Rocks

We will now observe the process of deposition a little more closely. Each of these two bottles contains the same amount of fine yellow clay, but in one the water is fresh, and i...

The principal accessory minerals occurring in limestone are: (1) _kaolin_, forming argillaceous or slaty limestone, which may be recognized by the argillaceous odor and dark col...

On a more regular coast, like that of New Jersey, the sediments are distributed with corresponding uniformity, the changes are less frequent and more gradual, and we have here a...

Minerals and rocks, or the inorganic portions of the earth, constitute the proper field or subject-matter of the science of Geology. Now the inorganic earth, like an animal or p...

3. _Argillaceous group._—Just as the conglomerate group shades off gradually into the arenaceous group, so we find it difficult to draw any sharp line of division between the ar...

Tachylite.—Tachylite is a highly basic volcanic glass, standing in the same relation to basalt and andesite that obsidian does to trachyte and rhyolite. It is much heavier than...

The arches of the strata are rarely distinctly indicated in the topography, but must be studied where the ground has been partly dissected, as in cliffs, gorges, quarries, etc....

COTEMPORANEOUS BEDS.—When the lava emitted by a crater is sufficiently liquid, it spreads out horizontally, forming a volcanic sheet or bed. If such an eruption is submarine, or...

Before proceeding to study particularly the various kinds of rocks, a little more preliminary work should be done. As already intimated, the more important characteristics of ro...

8. Calcite.—Carbonate of calcium: carbon dioxide (CO₂), 44; lime (CaO), 56; = 100. Hexagonal system, usually in rhombohedrons, scalenohedrons, or hexagonal prisms. Cleavage rhom...

Serpentine is often intimately associated with limestone and dolomite. The white veins running irregularly through the variety known as Verd Antique Marble, however, are not cal...

Important faults are rarely simple, well-defined fractures; but, in consequence of the enormous friction, the rocks are usually more or less broken and crushed, sometimes for a...

(4) _Vitreous texture._—The texture of glass, in which the constituent particles are absolutely invisible even with the highest powers of the microscope, and may be nothing more...

*41 Conglomerate: Breccia *42 “ Pudding-stone *43 Sand: Quartz °44 “ Magnetite *45 Sandstone: Ferruginous 46 “ Calcareous 47 “ Arkose *48 Quartzite 49 Clay: Boulder °50 “ Fire *...