Gold

Hardness: 2.5-3 on Mohs scale; Color: Golden yellow, brass yellow; Luster: Metallic; Crystal Structure: Isometric (typically dodecahedral or octahedral crystals); Cleavage: None; Specific Gravity: 19.3

Gold forms primarily through hydrothermal processes, where hot, mineral-rich fluids circulate through cracks and fissures in the Earth's crust, depositing gold as they cool. It is also found in placer deposits, where gold eroded from primary sources is concentrated in riverbeds and streambeds due to its high density.

Predominantly used in jewelry due to its malleability, ductility, and luster. Also critical in electronics for its excellent conductivity and corrosion resistance, in dentistry, and as an investment or monetary standard.

Gold has been prized by civilizations for millennia due to its rarity, beauty, and resistance to corrosion. It is one of the densest naturally occurring elements. Gold can be stretched into a wire of 1 inch from just a single gram, and beaten into a sheet 5 microns thick where around 100 sheets could be stacked on top of each other to be equal to the thickness of one human hair. It also has excellent electrical conductivity.

In the field, gold can be identified by its distinctive metallic golden-yellow color, high density (it feels unusually heavy for its size), and softness (it can be easily scratched). It does not tarnish. Found globally in minor amounts, but significant deposits are found in South Africa, Australia, the United States (Nevada, Alaska), Canada, Russia, and China. Prospectors often look for gold in alluvial deposits or in quartz veins within metamorphic and igneous rocks.