Cambrian, Ordovician and Silurian beds have been recognized, the Upper Cambrian consisting of a limestone which is very rich in metalliferous ores (especially galena and calamine).
Cables have frequently been picked up showing after many years of submergence no appreciable deterioration in this respect, while in other cases ends have been picked up which in the course of twelve years had been corroded to needle points, the result probably of metalliferous deposits in the locality.
Barytes is of common occurrence in metalliferous veins, especially those which yield ores of lead and silver; some of the largest and most perfect crystals of colourless barytes were obtained from the lead mines near Dufton in Westmorland.
The hornsilvers all occur under similar conditions and are often associated together; they are found in metalliferous veins with native silver and ores of silver, and are usually confined to the upper oxidized parts of the lodes.
Since the mineral occurs in definite veins, a more satisfactory and economical method of working would be that adopted in metalliferous mines, with a vertical shaft, cross-cuts, and levels running along the strike of the vein: the mica could then be extracted by overhead stopping, and the waste material used for filling up the worked-out excavations.
The outcrop of a metalliferous vein frequently manifests itself as a line of rocks stained with oxide of iron, often honeycombed and porous, the " gossan " or " eisen-hut," the iron oxide of which results from the decomposition of the pyrites, usually present as a constituent of such veins.
On the other hand, in the case of less regular deposits, including most metalliferous veins, and especially those of the precious metals, the uncertainty is often very great, and it is sometimes necessary to work on a small scale for months before any considerable expenditure of money is justified.
In the case of metalliferous deposits of varying thickness or irregular distribution the information from bore-holes is less satisfactory.
Of a metalliferous vein is generally more or less altered by oxidation, and often a part of the valuable mineral has been converted into a soluble form and leached out.
Four distinct types of reef gold deposits may be distinguished: (I) Gold may occur disseminated through metalliferous veins, generally with sulphides and more particularly with pyrites.
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.
Bismuth occurs in metalliferous veins traversing gneiss or clay-slate, and is usually associated with ores of silver and cobalt.
Mispickel occurs in metalliferous veins with ores of tin, copper, silver, &c. It is occasionally found as embedded crystals, for example, in serpentine at Reichenstein, Silesia.
The mineral is also met with in metalliferous veins, though much less frequently than pyrites; for example the "cockscomb pyrites" of the lead mines of Derbyshire and Cumberland.
The graphite veins in the older crystalline rocks are probably akin to metalliferous veins and the material derived from deep-seated sources; the decomposition of metallic carbides by water and the reduction of hydrocarbon vapours have been suggested as possible modes of origin.
Galena is of wide distribution, and occurs usually in metalliferous veins traversing crystalline rocks, clay-slates and limestones, and also as pockets in limestones.
The chief metalliferous deposits of the range are of mercury at New Almaden, not far south of San Francisco.
The metalliferous portion of the lode was similarly distributed in great masses, known as bonanzas.
Metalliferous ores of various kinds occur both in Nova Scotia and in this province, but with the exception of the gold already mentioned, have not yet become the objects of important industries.
Though petroleum and salt occur in the southwest peninsula of Ontario, metalliferous deposits are wanting, and the real wealth of this district lies in its soil and climate, which permit the growth of all the products of temperate regions.
Blende occurs in metalliferous veins, often in association with galena, also with chalcopyrite, barytes, fluorspar, &c. In oredeposits containing both lead and zinc, such as those filling cavities in the limestones of the north of England and of Missouri, the galena is usually found in the upper part of the deposit, the blende not being reached until the deeper parts are worked.
The Californian discoveries had given rise to a general search for metalliferous deposits in the Atlantic states, and this had been followed by wild speculations.
It occurs in metalliferous veins, often in association with iron-pyrites, chalybite, blende, &c., and in Cornwall and Devon, where it is abundant, with cassiterite.
The granulite, also called eurite and halleflinta, is the most important of the Pre-Cambrian formation, as it contains all the metalliferous deposits of Sweden.
The metalliferous deposits have generally the form of beds or layers between the strata of granulite and limestone.
These mines gave employment to 4 6, 59 2 labourers, of whom 24,445 were employed by the nitrate companies, 13,710 in various metalliferous mines, 6437 in coal mines, and 2000 in other mines.
SOLI, a Greek city on the north coast of Cyprus, lying at Soliais in the metalliferous country round Karavortasi near Lefka, on the south side of Morphou Bay.
The mineral occurs in metalliferous veins in the lead mines of Strontian in Argyllshire, Pateley Bridge in Yorkshire, Braunsdorf near Freiberg in Saxony; abundantly in veins in calcareous marl near Minster and Hamm in Westphalia; and in limestone at Schoharie in New York.
Native arsenic occurs usually in metalliferous veins in association with ores of antimony, silver, &c.; the silver mines of Freiberg in Saxony, St Andreasberg in the Harz, and Chanarcillo in Chile being well-known localities.
The older rocks are in many places peculiarly rich in metalliferous ores of all kinds.
The Shumadia is mainly occupied by rocks of Tertiary age, with intervening patches of older strata; and the Rudnik Mountains are traversed by metalliferous veins of syenite.
Metalliferous veins are common, amongst the best-known being the silver-bearing lead veins of Klausthal, which occur in the Culm or Lower Carboniferous.
Native silver is occasionally met with in metalliferous veins, where it has been formed by the alteration of silver-bearing minerals.
Metalliferous products containing silver arise in many operations; the chief products which may yield silver economically are copper and lead mattes, burnt argentiferous pyrites and certain drosses and scums. Argentiferous ores consist of silver-bearing base-metal minerals and gangue.