What does quartz mining mean

About quartz crystals

quartz (scientific name: Deep quartz or α-quartz) is a mineral with the chemical composition SiO2 and trigonal symmetry. It is the stable form (modification) of silicon dioxide on the earth's surface and, after the feldspars, the second most common mineral in the earth's crust. With a Mohs hardness of 7, quartz is one of the hard minerals and serves as a reference value on the Friedrich Mohs scale, which goes up to 10 (diamond). It often forms well-developed crystals of a great variety of shapes and colors, the crystal surfaces of which have a glass luster. Quartz cannot be split, it breaks like glass and has a greasy sheen on the broken surfaces.

Quartz is one of the most important minerals in industry and is of global importance both as a building material and as a raw material for the ceramic, glass and cement industries. Quartz sand is the raw material for the extraction of silicon. In addition, quartz and its colored varieties have long been valued as a gemstone.

Quartz crystals are also produced artificially: oscillating quartz crystals cut from them serve as clock generators in electronic circuits and quartz watches.

 

Piezoelectricity
Quartz shows a strong piezoelectric effect perpendicular to the prism axis along the a-axes. A quartz crystal reacts to pressure or tension with an electrical polarization along the direction of the force. Conversely, the application of an electrical direct voltage leads to an expansion or compression of the crystal. If an alternating voltage with a suitable frequency is applied, the crystal can be excited to vibrate in resonance. The resonance frequency depends on the geometry (shape and size) of the crystal. Due to the regularity and accuracy of these oscillations, quartz oscillators are used in quartz oscillators as a time base and clock generator for electronic circuits, for example in clocks, computers, digital and radio technology devices.

 

Use of the piezoelectric properties
Artificially drawn quartz single crystals are used, among other things, for piezoelectric applications. The piezoelectric properties of quartz are used in quartz oscillators, which, similar to a tuning fork, vibrate mechanically at a fixed frequency when excited by an electrical voltage. This made it possible to build very precise quartz watches. Quartz oscillators can be found as clock generators in practically all electronic devices today. In addition, quartz is also suitable for pressure measurements, in high-frequency technology and as an acousto-optical Q switch in lasers.

The two chiral forms of quartz, right quartz and left quartz, show an opposing piezoelectric effect. In such twins, therefore, the piezoelectric effects cancel each other out in the overall crystal, which is why they are useless for piezoelectric applications and are used less often than synthetic quartz crystals. For technical applications, the twins are often cut parallel to the (01-1) plane (AT section) or (023) plane (BT section), since the piezoelectric effect perpendicular to these planes is almost independent of the temperature.

(from Wikipedia http://de.wikipedia.org/wiki/Quarz)