Silicon dioxide (quartz) in various modifications is an essential component of the sands on earth. After the feldspars, quartz is the second most abundant mineral in the earth's crust. It is a hard mineral and forms diverse crystals, which differ in form and color. Quartz occurs when silicate rock melts crystallize (cool down). Thus, it is also a component of many igneous rocks.

Especially its piezoelectric effect has made quartz for an essential element of many electrical circuits (clock, computer, oscillator). When an alternating voltage is applied to crystals, they begin to pulsate what makes them applicable as a clock generator. The other way around: if the mineral is compressed or pulled, it frees electric charge.
Because of its high strength and resistance to almost all acids (excluding hydrofluoric acid) it is used in the chemical industry, the food industry and the optic.

In addition to the degradation of natural resources, especially in open pit, quartz sand is sucked up by ship from lakes. Then the separation by grain sizes is done using different methods. The silica itself is produced by the chemical decomposition of the silica sand under high temperatures. It falls out from the sodium or potassium carbonate solution (precipitated SiO₂). Alternatively, the deposition takes place during the combustion of silanes or silicon chloride under detonating gas (explosive mixture of hydrogen and oxygen). This SiO₂ is thus called pyrogenic silica.

Quartz crystals themselves can also be produced artificially and are used due to their piezoelectric properties as clock generator in various electronic devices; the most famous one is the quartz watch.

Quartz is the main raw material for the glass industry, but also significantly for the ceramic and concrete industry. However, it is rarely used in pure form in glassmaking, but with the addition of various metal and mineral oxides. This reduces the melting point and improves and varies the properties.
The high temperature resistance and high UV transmittance predestines quartz glasses as lenses, prisms or trays for use in laboratories. For concrete manufacturing, silicon dioxide in the form of silica fume is used as an additive for high performance and ultra high performance concretes. Even as a food additive (E551) or in the liquid during fracking certain quartz sands are used. More various applications: pharmaceuticals, cosmetics, agriculture, automobile industry.

In the jewelry industry, various quartz variations are used depending on the shape and color. Famous ones are Agate (striped disks), Amethyst (purple), Onyx (black and white starched), Jasper (red) and citrine (yellow).