Occurrence, use and possible substitution of quartz

Silicates constitute approximately 90 % of the earth crust. Silicon dioxide occurs as quartz (crystalline silicic acid) and silicates. Almost any natu ral inorganic raw material contains quartz. As quartz combines a number of unique physical properties, it has become an indispensable raw material for many traditional and high-technology applications. In many cases substitut ion is impossible due to technical, financial or logistic reasons. Wherever substitution is realised however - at least partly - a lower technical per formance level and/or higher costs must be accepted, and very often substit ution materials with a quartz content > 0.1 % are used. There is a large ra nge of industrial and commercial applications of quartz in different substa nces, preparations and products. In addition, quartz can be found everywher e in the human environment. It is well-known that long-term high-level expo sure to respirable quartz dust may cause silicosis. The long-established co -operation between the German Berufsgenossenschaften and the quartz-produci ng and quartz-processing industry shows that silicosis can be efficiently a voided as long as the applying maximum workplace concentrations (MAK-values ) are observed.