Glass is the ancient isotropic, inorganic substance which for the first time appeared in ancient Egypt and the countries of Western Asia. However, how its history was long and interesting, not all know about its versions, in particular, about mineral glass.
Mineral glass represents the melted quartz sand of natural origin with various additives. Ready glass has durability, resistance to radiations, excellent optical qualities and abrasive stability. Besides its great advantage is that it considerably reduces an ultra-violet stream. The form of mineral glass does not change over time. From all known materials intended for production of lenses, mineral glass is processed thanks to own durability much easier. Besides its own durability provides the visual perception free from deformations. It means that the lens provides own durability of points, and not just a frame.
Besides the optical industry, mineral glass is widely used at production of hours. Dials of 90% of all hours become covered by transparent protection from this glass. Probably, therefore also it is called "usual" because of its universal distribution. First of all it is caused by the fact that at loading from its admissible size glass at best will remain whole, and in the worst will just crack. However there are special technologies of processing of a surface of glass which increase its durability and do impregnable even to scratches.
Mineral glass thanks to its easy processing and large reserves of raw materials has rather low cost. Therefore it is issued in a large number and any sizes. It is contraindicated to children, drivers and actively having a rest people to wear glasses from mineral glass as at heavy blow it can break into the smallest splinters and damage an eye crystalline lens. In addition, glass has the increased weight which can lead to discomfort when carrying lenses from this material.