Dianne Hackett, age 12, of Richmond, Va., for her questions
What exactly is gold?
The Indians of Mexico thought that the conquering Spaniards had a disease which only gold could cure. Almost everyone in the Old World also believed that enough gold would solve all their problems. For many generations they toiled, traded, plundered, made war for gold and even spent fruitless hours trying to make it from baser metals.
The reasons why gold was considered so highly are not hard to find. It is scarce and not easy to come by. This makes it valuable. It is a very durable metal; it does not rust and acids do not normally corrode it. Gold will dissolve only in a mixture of nitric acid and hydrochloric acid. This powerful mixture was named aqua regia, meaning royal water because it is the only liquid in which gold, the king of metals, can be dissolved.
Gold, however, is not a hard metal. In fact it is one of the softest of all minerals. It rates 2.5 on the standard scale of mineral hardness. Talc, one of the softest of minerals, rates 1 on this scale and diamond, the hardest of natural stones, rates 10. Because of its softness, pure gold is easily chipped and even in olden days it was mixed or alloyed with other metals to make it more lasting.
The softness of gold, however, makes it the easiest of all metals to work. It can be pressed into leaves no thicker than one 25,OOOth part of an inch. This means that it is the most malleable of all metals. It can also be drawn into long thin threads for, say, making gold lace. An alloy of gold and silver can be drawn to a thread one 20,OOOth .part of an inch wide. This means that gold is the most ductile of metals.
In olden days, its scarcity, its durability and its workability made gold the most valuable of metals. Add to this the fact of its sunny beauty and you can see why it played such a 1ong and honorous role in the minds of mankind.
Today; gold is not the; rarest of metals and not the most valuable. Too, we know more about it. We know, for instance, that it is an element one of the 90 odd chemicals from which everything in our world is made. Every atom of gold is like every other ‑ we cannot make them from other atoms.
We know too that gold is very heavy and this fact helps us to sift it from other minerals in the earth's crust. When a prospector finds the right stream bed he shakes around a pan of muddy water so that the heavier particles sink and the lighter particles come to the top. If there is gold in the mixtures it will be at the bottom of the pan. For gold is seven times heavier than sandy quartz and more than twice as heavy as solid iron.
Though we no longer make gold coins, we use paper money. We use gold for its beauty to make ornaments and jewelry. We overcome its softness by alloying it with metals such as silvery platinum, copper, nickel and zinc. A carat is the 24th part of any gold metal or gold alloy. Hence, 24 carat gold is pure gold 18 carat gold is six part alloy metal and 12 carat gold is half alloy metal.