Opal This essay discusses some characteristics and history of the opal.

Opal is the modern October birthstone and the accepted gem for the 13th wedding anniversary. al to the highest degree opals argon between 50-65 million years old, date fundament to the Cretaceous period when dinosaurs roamed the earth. Opal formed as silicon dioxide from decomposing rocks motley with ground water which formed a silicon dioxide gelatin that collected and hardened in underground cavities and fissures. in that respect are devil distinct showcases of opal, special K and precious. The way the silica particles form de bourneines which type. In precious opal, silica particles are jammed in fastness rows and layers. Moving the stone causes fresh to diffract, or split, as it grazes the opal surface. This light diffusion shows iridescent flashes of green, blue, aqua and sometimes yellowish or red colors which are referred to as fire. Black Opal comes from the Lightning Ridge component of Northern New southern Wales. It is the most rare and most valuable opal. F ine musical note black opals often embody more per carat than diamonds. The term black opal is misleading because the opal is not actually black, but sort of has a very Cimmerian base. This dark base enhances the glorious colors know as fire. Light opal is the most common type of opal found and refers to both the watch crystal type opal (translucent) and the milky opal (opaque).

It is the most common variety and is in the primary(prenominal) less valuable than gem quality light opal. bright colored light opals may be quite pricy with a value exceeding some Black and bowlder Opals. Brilliance or luster is one of the primary factors that determines an opals value. An opal with h ard intensity level and color adds more val! ue. The hardness af an opal is between 5.5 and 6.5 on Mohs scale. Most opals are found where geothermal heatable springs dried up during seasonal periods of rainfall and... If you want to raise a full essay, nine it on our website: OrderEssay.net

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