Gold is a universally recognized and highly valued metal, admired for its luster and enduring historical significance. Its radiant appearance has captivated cultures globally, serving as a symbol of wealth and power for millennia.
The Gold Element
Gold is a chemical element, a pure substance that cannot be broken down into simpler chemical constituents. Its chemical symbol is Au, derived from “aurum,” the Latin word for gold. Each gold atom has a unique atomic number of 79, meaning it contains 79 protons in its nucleus.
In a neutral gold atom, the number of electrons orbiting the nucleus also matches the number of protons. This specific arrangement defines gold and differentiates it from all other elements in the universe. Regardless of whether gold originates from Earth or a distant celestial body, its atomic structure remains constant.
Cosmic Origins
Gold, an element heavier than iron, forms under extreme conditions not found within stars. Scientists believe gold is primarily forged during cataclysmic cosmic events like violent neutron star collisions (kilonovas) or massive star explosions (supernovae). Recent research suggests neutron star mergers are particularly significant for producing heavy elements.
During these events, rapid neutron capture (the r-process) occurs. Atomic nuclei absorb many neutrons, creating elements heavier than iron, including gold. This newly formed gold is ejected into space, becoming part of the cosmic dust and gas that forms new stars and planetary systems. Earth’s gold likely originated from these ancient stellar events.
Understanding Gold Purity
The gold encountered in daily life is often not entirely pure. Purity is measured using the karat system, where 24 karat (24K) represents 99.9% pure gold. Pure 24K gold is exceptionally soft and malleable, which makes it generally unsuitable for durable items like jewelry, as it can easily scratch or deform.
To enhance its strength, durability, or alter its color, pure gold is frequently mixed with other metals, forming an alloy. Common metals alloyed with gold include copper, silver, zinc, and nickel. For example, 18K gold contains 75% pure gold and 25% other metals, while 14K gold consists of 58.3% pure gold and 41.7% other metals. These alloys create a material that balances gold’s beauty with practical wearability.