Thirty-eight years later, his hunch was proven correct. The physical properties of gold add to its popularity and value. So gold is relatively soft, malleable and tarnish resistant. It makes excellent jewelry. The brightness and ornamental beauty of gold have fascinated humans for more that 5,000 years and still does.
Gold often establishes the standard by which wealth is measured.
Gold has an average specific gravity of 19.3, meaning it is 19 times as heavy as an equal volume of water. Contrast this with the specific gravity of gravel, 2.7, or lead, which has a specific gravity of 11. Gold is relatively easy to recognize when you know its properties, but novices can confuse it with minerals such as pyrite or mica. Although gold is normally opaque, very thin sheets let through a feeble, greenish color, and coating a few molecules in thickness is used to protect astronauts and pilots vision. The fusion point of gold is 1942 degrees F, and it is insoluble in acids, except aqua regia.