Note: Information is dated. Do not rely on it.Gold. On account of its beautiful color and since it does not become tarnished or corroded in use, gold is considered the most precious of metals and is used as the principal basis of value throughout the civilized world. It has been known from time immemorial, and is found in many parts of the world. It is usually found in the metallic or native state in the form of nuggets or smaller particles, in sand or gravel, or distributed through rocks or veins. Nuggets weighing as much as 1,000 ounces have been found. Native gold usually contains some silver. The metal is also found in combination with tellurium as "telluride ore," and it frequently accompanies copper ores and iron pyrites. The extraction of gold from sands or gravels, called alluvial or placer mining, is accomplished by washing with water in various ways. The heavy gold sinks to the bottom when the material is stirred up with water, and mercury (quicksilver) is usually used to amalgamate the gold and hold it. Solid ores have to be powdered by stamp mills or other devices before the gold can be extracted, and sometimes they must be heated to redness (roasted) to drive off tellurium or other things. It is more than nineteen times as heavy as water. In malleability it stands first among the metals, being capable of being beaten to a thickness of 1-250,000 of an inch and ductile enough to be drawn into a wire 500 feet long and weighing only one grain. It may be alloyed with other metals to change the color for designs. The best known alloy of gold is that with copper, which is used for gold coins. The chief gold discoveries have been in California, 1848; Australia, 1851; British Columbia, 1858; New Zealand and Nova Scotia, 1861; South Africa, 1868; West Australia, 1870; South Australia, 1886; Alaska and Klondike. Important discoveries of gold were made in Porcupine, Canada, in 1910.