Examples of elaborate gold workmanship, many in nearly perfect condition, survive from ancient Egyptian, Minoan, Assyrian, and Etruscan artisans, and gold has continued to be a highly favored material out of which to craft jewelry and other decorative objects. Owing to its unique qualities, gold has been the one material that is universally accepted in exchange for goods and services. In the form of coins or bullion, gold has occasionally played a major role as a high-denomination currency, although silver has generally been the standard medium of payments in the world's trading systems. Although gold's official role in the international monetary system had come to an end by the 1970s, the metal remains a highly regarded reserve asset, and approximately 45 percent of all the world's gold is held by governments and central banks for this purpose. Gold is still accepted by all nations as a medium of international payment.
Gold is widespread in low concentrations in all igneous rocks.
Its abundance in the Earth's crust is estimated at about 0.005 parts per million. It occurs mostly in the native state, remaining chemically uncombined except with tellurium, selenium, and possibly bismuth. The element's only naturally occurring isotope is gold-197. Gold often occurs in association with copper and lead deposits, and, though the quantity present is often extremely small, it is readily recovered as a byproduct in the refining of those base metals. Large masses of gold-bearing rock rich enough to be called ores are unusual.