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.
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.
Bismuth occurs in metalliferous veins traversing gneiss or clay-slate, and is usually associated with ores of silver and cobalt.
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.
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.
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.
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.
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 metalliferous deposits have generally the form of beds or layers between the strata of granulite and limestone.
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.