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Mercury is found sparingly by itself in nature. However, it is often
combined as cinnabar (HgS), the widely known bright red pigment used in industry. It also forms amalgams with gold and silver. Liquid mercury is popularly called quicksilver, because of its silvery
colour, and because a globule of liquid rolls rapidly over a surface without wetting it. In this context, mercury's specific gravity was determined by Beruni to be 13.58, a meticulous calculation before the mideleventh century (fifth A.H.). The number today is considered to be 13.56 slightly lower by a fraction. Precious Metals
Gold is considered the king of metals. It is known in Arabic as the
nudar and when melted over strong fire freed from its impurities, it is then called 'iqyan, and the refined, genuine gold al-ibriz. Mining of the ore has been carried out by our ancestors in this region since 4000 B.C., if not earlier. In Arabic literature, poets compared the firing processes for gold's purification with moral refining through sorrows, trials and hardships. Rarefication, in like manner, results in a greater measure of maturity and spiritual wisdom, as Beruni also reiterated. Gold occurs in nature as an inert free metal, highly resistant to corrosion and defies all kinds of chemical destruction. Washed thoroughly
with water, pure gold is recovered by panning. It, nevertheless, forms soft alloys with copper, for example, giving it strength and hardness (designed as 14 or 18 carat gold mixed with 8 or 6 parts of copper for normal use). Gold also occurs with mercury in an amalgam-forming property. When the non-metal mercury is removed, what is left behind is a spongy, soft mass of quite pure gold. This precious metal being malleable can easily be beaten into very
thin leaves and sheets, or drawn into wires most convenient for conductive and other uses. This ore also forms alloys with silver and nickel as well. Only at the goldsmith shops is aqua regia (the royal water, a mixture of concentrated hydrochloric and nitric acids) employed for dissolving the precious metal. Gold, furthermore, is easily utilized in industry and trade, because
of its relative scarcity as Beruni's text indicates. It thus helps keep its monetary value high, yet enough is found to satisfy monetary markets, as well as the industries' various needs. Nevertheless, its rarefied and excellent qualities, and its aesthetic values assisted in establishing it as foremost among the coinage metals. Such considerations persisted over six millennia. Because of its long history, it remained in demand as a basis for the world's monetary system. It is sought, likewise, for praiseworthy jewellery and unrivalled ornamentations. Silver takes the second place to gold not only as a coinage metal,
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