Quartz is a silicon dioxide mineral (SiO₂) and one of the most abundant minerals on Earth. It has a Mohs hardness of 7, making it durable for various uses, including jewelry, carvings, and industrial applications. Quartz forms in igneous, metamorphic, and sedimentary rocks, often in crystal formations such as points, clusters, and geodes. It comes in many varieties, including amethyst (purple), citrine (yellow), rose quartz (pink), smoky quartz (brown to black), and clear quartz (colorless). Major sources include Brazil, Madagascar, the United States, and Switzerland.