Quartz 1

**Chemical composition:** SiO₂

**Hardness:** 7

**Density:** 2.6 g/cm³

**Crystal system:** Trigonal (α), Hexagonal (β)

**Luster:** Vitreous

**Info:** Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar. There are many different varieties of quartz, several of which are semi-precious gemstones, e.g., transparent pure quartz, pale pink rose quartz, grey smoky quartz, pale yellow citrine, purple amethys, black morion quartz, agate, onyx, heliotrope or jasper. Quartz is a very important rock-forming mineral.

## Keywords
mineral quartz texture color ornamental stone semi-precious gemstone