52 - Opal

Hello friends, 

Welcome to the Mineral Repository at the department of geology, Shivaji science college, Nagpur.

I am opal, I belong to a large group of minerals known as the “Silica family”. I am a hydrated amorphous form of silica with chemical composition SiO2 with "n" number of water molecules. The water content may range between 6% to 10%. Due to my amorphous property, I am classified as a mineraloid. The most common forms of Silica in our environment are crystals of Quartz and sand. I am a gemstone born from the earth’s vibrant depth. My name is derived from the Sanskrit word upala, which means 'jewel'. I am deposited at a relatively low temperature and I may occur in the fissures of almost any kind of rock. I am further divided into 2 groups, precious opal and common opal. Precious opal displays play-of-color defined as "a pseudo chromatic optical effect" resulting in my internal structure to diffract light, resulting in play-of-color, while on the other hand Common opal often displays a hazy milky turbid sheen form. Depending on the conditions in which I develop, I may be transparent, translucent, or opaque, and the background color may be white, black, or nearly any color of the visual spectrum. My black variety is extremely rarest, while white, gray, and green opals are the most common. I am mostly found in Australia and in Ethiopia. I am used in abrasives, insulation media, fillers, ceramic ingredients and as jewelry. As a stone of inspiration and creativity I shimmer and reflect the beauty of rainbow itself. 

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