Gold (native)

Gold is an element that is native platinum and has long been prized for the beauty, resistance to chemical attack and workability. It is often used by mankind for thousands of years as it is found as being a native element, includes a relatively low melting point (1063 degrees Celsius) and it is malleable. Gold is also used as a standard for international currency and is trusted in jewelry, electronics (where its superb properties as a conductor help offset its expense that is tremendous) dentistry and in photographic processes.

Gold does occur in significant amounts in three main types of deposits: veins of hydrothermal and beginning that is related to consolidated placer deposits and in unconsolidated placer deposits. It would likely additionally occur in granitic pegmatites, in contact deposits which are the metamorphic plus in hypo-thermal deposits. It really is commonly found as disseminated grains in Quartz veins with Pyrite and other sulphides, or as rounded grains, flakes or nuggets in placer deposits and in streams and rivers. Gold is normally panned from such deposits by taking advantageous asset of its density that is high to away the lighter sediments from a pan or sluice. 

Gold is immune to most acids, although it will dissolve in acid, a mix of aqua fortis and acid, that forms a soluble tetrachloroaurate anion. Gold is insoluble in aqua fortis, that dissolves silver and base metals, a property that has long been wont to refine gold and to verify the presence of gold in metallic objects, giving rise to the term assessment. Gold conjointly dissolves in basic solutions of cyanide, that are utilized in mining and electroplating. Gold dissolves in mercury, forming amalgam alloys, however, this is often not a chemical process.

There are numerous localities worldwide for fine gold specimens for mineral collectors and native Gold cabochons.

Chemical Formula: Au
Crystallography: Isometric – Hexoctahedral
Crystal Habit: As octahedra, dodecahedra, and cubes, typically crude or rounded, to about 5 cm. In twinned and parallel crystal groups; reticulated, dendritic, arborescent, platy, filiform, spongy; massive, and in rounded nuggets; scales and flakes.
Twinning: Common on [111]; repeated to form reticulated and dendritic aggregates.

 

Cleavage: None Observed
Fracture: Hackly, Jagged
Tenacity: Highly Malleable and Ductile
Hardness (Mohs): 2.5 – 3.0
Density: 19.30 (g/cm3)
Luminescence: None
Radioactivity: Not Radioactive
Other: Highly Conductive

 

Color: Yellow, pale Yellow, Orange, Yellow White, Reddish White
Transparency: Opaque
Luster: Metallic
Refractive Index: R: (400) 36.8, (420) 36.8, (440) 36.4, (460) 36.1, (480) 36.7, (500) 45.3, (520) 62.5, (540) 75.0, (560) 82.2, (580) 86.8, (600) 89.7, (620) 91.9, (640) 93.3, (660) 94.1, (680) 94.8, (700) 95.3
Birefringence: 0.00 (Opaque)
Pleochroism: None