Quartz is a hard, glossy mineral made of silicon and oxygen. It is found in most kinds of rocks in colourless, often transparent form. There are also coloured varieties including semi-precious stones such as amethyst and citrine. Pure quartz is called rock crystal also. In appearance it looks like glass. It has six-sided crystalline structure. It ranks 7 on the Mohs’ scale of hardness and is resistant to chemical or mechanical breakdown.

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