The metalliferous deposits are peculiar to particular rocks: gold and tin are most plentiful in granite and the rocks lying immediately above it; copper is deposited in various slate formations resting on the preceding, and in the trias; lead is found in the mountain-limestone system, and is rare where iron and copper abound; iron abounds in the coal and oolitic strata, and in a state of oxidule and carbonate in the older rocks; and silver is found in almost all of these formations; its ores being frequently combined with those of other metals, especially of lead and copper. There is such a connection between the contents of a vein and the nature of the rock in which the fissure is, that, when in the oldest rocks the same vein intersects clay-slate and granite, the contents of the parts enclosed in one rock differ very much from what is found in the other. It is believed that in the strata lying above the coal-measures none of the more precious metals have been found in England in such plenty as to defray the expense of raising them, although such a rule does not extend to the continent of Europe or to South America, where copper and silver ores abound in our new red sandstone series. In Great Britain no metal is raised in any stratum newer than the magnesian limestone. Metals exist chiefly in the primary and early secondary strata, especially near the junction of the granite and slates; and it is a fact that rich veins of lead, copper, tin, &c., abound only in and near the districts which have been greatly shaken by subterraneous movements. In other countries, as Auvergne and the Pyrenees, the presence of igneous rocks may have caused mineral veins to appear in more recent strata than those which contain them in Great Britain.