"Quartz is a widely distributed mineral found at Earth's surface. It is present and plentiful in all parts of the world. It is abundant in igneous, metamorphic, and sedimentary rocks.
This durability makes it the dominant mineral of mountaintops and the primary constituent of beach, river, and desert sand. Quartz is ubiquitous, plentiful and durable. Minable deposits are found throughout the world.
Quartz makes an excellent gemstone. It is hard, durable, and usually accepts a brilliant polish. Popular varieties of quartz that are widely used as gems include: amethyst, citrine, rose quartz, smoky quartz, and aventurine. Agate and jasper are also varieties of quartz with a microcrystalline structure."