| Gold |
| Every body most know about this famous word "GOLD". But do you know why gold is so important for mankind..?. You can get brief information about history of gold from here. |
| Properties Mineral Name : Gold / Electrum Chemical Composition: Au (Native elements) / Au-Ag alloy Crystal System: Cubic / Isometric Physical properties : Yellow color, varying in brightness depending on the impurities. Normally occurs in very small, shapeless grains, sheets and flakes. Fairly soft (Mohs scale hardness 2.5-3), very heavy (specific gravity 19.3), ductile and malleable. Opaque with bright metallic luster Optical properties : Reflectance and Colour: Air:Strong: bright or golden yellow; electrum is slightly lighter and less yellow Oil:Strong: bright or golden yellow; electrum is slightly lighter and less yellow Polishing cleavage: not visible R% (reflectivity) : 71.5 VHN (hardness) :53 - 58 Polishing Hardness :Soft: (2.5 - 3) Pleochroism Air: none pleochroic Oil: none pleochroic Anisotropism: Isotropic but incomplete extinction: a greenish shade is often observed Internal Reflections: None Twinning: (111) common Associated Minerals: Arsenopyrite, berthierite, calaverite, chalcopyrite, cinnabar, cobaltite, niccolite, pitchblende, pyrite, sperrylite, stibnite, tellurides, ullmanite, uraninite Key Identification Criteria: Golden yellow color, extremely strong reflectance, and softness are characteristic. Occurs as isolated grains and veinlets in many sulfides (especially in pyrite and arsenopyrite). Electrum contains 20% or more silver causing the color to be more whitish and the reflectance to increase |
| Used of Gold : The main source of the commercial metal, used mainly as a monetary standard, in jewelry, in dentistry and for scientific and electronic instruments. |
| Genesis of gold: |
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