Quartz

Introduction: Quartz is one of the most common minerals on earth which itself is a rock-forming mineral in sedimentary, metamorphic and igneous rocks. It occurs in a large diversity of colours with a number being mined as gemstones including amethyst, 'tiger's eye', citrine and carnelian. Hexagonal crystals are the most common, although other habits include amorphous opalline quartz, finely banded layers of agate and tiger's eye'. Both building sand and glass contain silica and silicon chips are used in the computer and electronics industries.

Composition: Silicate

Crystal system: Hexagonal

Lustre: Vitreous

Streak: White

Hardness: 7