How Is Gold Found?
Probably the first metal known to man was gold. Because of the way it occurs in nature, man knew about it and valued it long before the days of recorded history! Just how is gold found?
Even though it's considered so precious and rare, gold is actually widely distributed in nature. The trouble is that in most cases there isn't enough gold present to make it profitable to extract it. For example, sea water contains a small amount of gold. But it's so tiny in quantity that no one knows how to separate gold from the sea. Yet there's so much water in the oceans that the total amount of gold in them might be as much as ten thousand million tonnes!
Gold occurs in two forms: native, which means it's not combined with
other minerals, and in combination with the ores of other metals.
Native gold occurs mostly in veins of quartz or in masses of iron
Sometimes the quartz or pyrites have been exposed to water and wind. The particles of rock surrounding the lumps of gold have been washed away, leaving lumps or nuggets of nearly pure gold.
The nuggets are gradually washed down to the bottom of the valleys and become mixed with the sand and the gravel. In this form it is called "alluvial" or "placer" gold. When man first discovered gold, it was placer gold. These particles of gold vary in size from fine dust to the great nugget found in Australia, the "Welcome Stranger" nugget, weighing nearly 70 kilos.
Gold is often found in the ores of other metals. Silver nearly always contains quantities of gold. Copper ores quite frequently occur in combination with gold.
Today, most of the gold is obtained by mining methods similar to those used for other metals. A deep hole, called a shaft, is dug into the ground toward the gold deposit. This may be more than a mile deep! The ore is then blasted, loaded on carts, brought to the shaft, and hoisted to the surface. It is crushed and ground into a fine sand called pulp, and then by means of chemical action, the gold is extracted from the other material.
The three principal gold-producing countries of the world are South Africa, Russia, and the United States.