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- Gold is the only metal that is yellow or “golden”. Other metals may develop a yellowish color, but only after they have oxidized or reacted with other chemicals.
- Nearly all of the gold on Earth came from meteorites that bombarded the planet over 200 million years after it formed.
- The element symbol for gold is Au. The symbol comes from the old Latin name for gold, aurum, which means “shining dawn” or “glow of sunrise”. The word “gold” comes from the Germanic languages, originating from the Proto-Germanic gulþ and Proto-Indo-European ghel, meaning “yellow/green”. The pure element has been known since ancient times.
- Gold is extremely ductile. A single ounce of gold (about 28 grams) can be stretched into a gold thread 5 miles (8 kilometers) long. Gold threads can even be used as embroidery thread.
- Malleability is a measure of how easily a material can be hammered into thin sheets. Gold is the most malleable element. A single ounce of gold can be beaten out into a sheet that is 300 square feet. A sheet of gold can be made thin enough to be transparent. Very thin sheets of gold may appear greenish blue because gold strongly reflects red and yellow.
- Although gold is a heavy, dense metal, it is generally considered non-toxic. Gold metal flakes may be eaten in foods or drinks.
- 24 karat gold is pure elemental gold. 18 karat gold is 75% pure gold. 14 karat gold is 58.5% pure gold, and 10 karat gold is 41.7% pure gold. The remaining portion of the metal usually is silver, but may consist of other metals or a combination of metals, such as platinum, copper, palladium, zinc, nickel, iron, and cadmium.
- Gold is a noble metal. It is relatively unreactive and resists degradation by air, moisture, or acidic conditions. While acids dissolve most metals, a special mixture of acids called aqua regia is used to dissolve gold.
- Gold has many uses, aside from its monetary and symbolic value. Among other applications, it is used in electronics, electrical wiring, dentistry, electronics, medicine, radiation shielding, and to color glass.
- High purity metallic gold is odorless and tasteless. This makes sense since the metal is unreactive. Metal ions are what confers flavor and odor to metallic elements and compounds.