Rock_crystal

Quartz is a hard, crystalline mineral composed of silicon atoms. The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra , with each oxygen being shared between two tetrahedra, giving an overall chemical formula. Quartz is the second most abundant mineral 's continental crust

Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation from α-quartz to β-quartz takes place abruptly at 573 °C (846 K; 1,063 °F). Since the transformation is accompanied by a significant change in volume, it can easily induce fracturing of ceramics or rocks passing through this temperature threshold.

There are many different varieties of quartz, several of which are semi-precious gemstones. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings.

Quartz is the mineral defining the value of 7 on the Mohs scale of hardness method for determining the hardness of a material to abrasion.