Auriferous sentence example
The extraction of gold from auriferous minerals by fusion, except as an incident in their treatment for other metals, is very rarely practised.
There are occasional bands of conglomerates, sometimes auriferous.
Auriferous quartz is worked by a foreign company in its neighbourhood.
The gold and platinum mines of Choco were on some of its affluents, and the river sands are auriferous.
All these small rivers are described as auriferous and have attracted attention for this reason.Advertisement
Theconglomerates are true " banket " and are auriferous, but the gold has not been met with in payable quantities.
The sand of some of the rivers, as for instance the Maros, Szamos, Koros and Aranyos, is auriferous.
They may safely be considered to be among the oldest auriferous sediments of the world.
The whole range is highly auriferous, and the thickness of the strata is not less than 10,000 ft.
Modern methods of hydraulic mining have been introduced to work the auriferous banks of Poto; elsewhere antiquated methods only are employed.Advertisement
The minerals of the second class, usually spoken of as " auriferous," are comparatively numerous.
The genesis of the last three types of deposit is generally assigned to the simultaneous percolation of solutions of gold and silica, the auriferous solution being formed during the disintegration of the gold-bearing metalliferous veins.
The formation is noted for its regularity as regards both the thickness and the gold-tenor of the ore-bearing reefs, in which respect it is unparalleled in the geology of the auriferous formations.
So certain is the ore-bearing formation that engineers in estimating its auriferous contents feel justified in assuming, as a factor in their calculations, a vertical extension limited only by the lowest depths at which mining is feasible.
In alluvial deposits the richest ground is usually found in contact with the "bed rock"; and, when the overlying cover of gravel is very thick, or, as sometimes happens, when the older gravel is covered with a flow of basalt, regular mining by shafts and levels, as in what are known as tunnel-claims, may be required to reach the auriferous ground.Advertisement
In working auriferous river-beds, dredges have been used with considerable success in certain parts of New Zealand and on the Pacific slope in America.
It was at one time proposed to treat the concentrated black iron obtained in the Ural gold washings, which consists chiefly of magnetite, as an iron ore, by smelting it with charcoal for auriferous pigiron, the latter metal possessing the property of dissolving gold in considerable quantity.
Many processes have been suggested in which the gold of auriferous deposits is converted into products soluble in water, from which solutions the gold may be precipitated.
One process depends upon the fact that, with a suitable current density, if a very dilute solution of silver nitrate be electrolysed between an auriferous silver anode and a silver cathode, the silver of the anode is dissolved out and deposited at the cathode, the gold remaining at the anode.
The Louisiade and the d'Entrecasteaux Islands consist of the same slates and schists as form the main axis of the eastern peninsula, and they are auriferous.Advertisement
No auriferous reefs have been found.
Even the Calaveras man is no exception, since his skull and his polished conical pestle, the latter made of stone more recent than the auriferous gravels, show him to have been of Digger Indian type.
Frequently in districts where slates are much crumpled they are traversed by numerous quartz veins, which have a thickness varying from several inches up to many feet, and may occasionally be auriferous.
Other auriferous gravels are buried under the upland lava flows, and are now reached by tunnels driven in beneath the rim of the table mountains.
The development of the coal and iron interests, and the increasing importance of the gold product of the Appalachian auriferous belt, and also of the lead product of the Mississippi Valley, led to a more general and decided interest in geology and mining; and about 1830 geological surveys of several of the Atlantic states were begun, and more systematic explorations for the ores of the metals, as well as for coal, were carried on over all parts of the country then open to settlement.Advertisement
In five years from the discovery of gold at Coloma on the American river, the yield from the auriferous belt of the Sierra Nevada had risen to an amount estimated at between sixty-five and seventy millions of dollars a year, or five times as much as the total production of this metal throughout the world at the beginning of the century.
A series of quartzites and slates referred to the Cambrian, and holding numerous and important veins of auriferous quartz, characterize its Atlantic or southeastern side, while valuable coal-fields occur in Cape Breton and on parts of its shores on the Gulf of St Lawrence.
Limonite often forms a cementing medium in ferruginous sands and gravels, forming "pan"; and in like manner it is the agglutinating agent in many conglomerates, like the South African "banket," where it is auriferous.
The railway to Kumasi from Sekondi, which was completed in 1903, passes through the auriferous region.
Gold (also platinum) is a not infrequent associate, but this may only mean that the sands in which the diamond is found have been searched because they were known to be auriferous; also that both gold and diamond are among the most durable of minerals and may have survived from ancient rocks of which other traces have been lost.Advertisement
Auriferous alluvial strata have been discovered in various localities, but everywhere the scarcity of water has been a bar to their being exploited with profit.
Only in the auriferous and civilized frontier districts of India (the Punjab) did a system of coinage find early acceptance.
The Yarkand-Darya and its numerous tributaries, which are fed by the glaciers of the mountain regions, as also many rivers which are now lost in the steppe or amidst the irrigated fields, bring abundance of water to the desert; one of them is called Zarafshan ("gold-strewing"), as much on account of the fertility it brings as of its auriferous sands.
The Witwatersrand series of the Transvaal includes auriferous conglomerates which have been worked since 1886 and constitute the richest gold-mines in the world.
The district is both auriferous and coal-bearing.Advertisement
Lead, wolfram, antimony and auriferous quartz exist in the districts of Coimbra, Evora, Beja and Faro.
Traces of auriferous sands have been discovered at many places, but the percentage of gold is too poor to make the working remunerative.
Gold is found almost all over the region of crystalline rocks, except in and around the Antsihanaka province, the richest auriferous districts being a band of country parallel with the east coast and spreading at its southern end into the interior; and another tract, whose centre is about 100 m.
The idea is exploded that auriferous loded that auriferous lodes necessarily improve in value with depth.
Not only in these lucky provinces, New South Wales and Victoria, where the auriferous deposits were revealed, but in every British colony of Australasia, all ordinary industry was left for the one exciting pursuit.Advertisement
Water is poured on the dirt, and the rocking motion imparted to the cradle causes the finer particles to pass through the perforated bottom on to a canvas screen, and thence to the base of the cradle, where the auriferous particles accumulate on transverse bars of wood, called " riffles."
The auriferous region is stated to be about 25 sq.
This expedition put an end to the hope, so long entertained, that it was possible to obtain a direct and practicable route for stock between Kimberley and Coolgardie gold-fields; and it also proved that, with the possible exception of small isolated patches, the desert traversed contained no auriferous country.
Auriferous sands, but not very rich, have been discovered in the feeders of Lake Hanka and the Suifong river, as also on the smaller islands of the Gulf of Peter the Great.
Other auriferous reefs are found all along the eastern escarpment of the Drakensberg and are worked in the De Kaap (Barberton) district, on the Swaziland frontier, in the Lydenburg district, in the Murchison Range and in other places in the Zoutpansberg.Advertisement
Gold is often present, and in many gold-mining districts the precious metal is obtained mainly from auriferous pyrites.
Gold was washed from some of the Portuguese rivers before the Christian era, and among the Romans the auriferous sands of the Tagus were proverbially famous; it is, however, extremely improbable that large quantities of gold were ever obtained in this region, although small deposits of alluvial gold may still be found in the valleys of the Tagus and Mondego.