Chemistry, textures and physical properties of quartz — geological interpretation and technical application

Abstract Quartz is one of the most abundant minerals in the Earth’s crust and the most important silica mineral, occurring in large amounts in igneous, metamorphic and sedimentary rocks. The mineral is widely used as a raw material in several industrial applications. Because of its chemical composition (SiO 2 ) and its specific properties, quartz can be used both as a bulk product (e.g. quartz sands in the glass or foundry industry) and as a high-tech material (e.g. piezo or optical quartz). Dependent on the specific conditions of either natural or synthetic formation, quartz can display typomorphic properties. Variations in crystal shape, specific micro-structure, trace element or isotope compositions, characteristic spectroscopic properties, etc. may be controlled by the genesis of the quartz involved. Accordingly, the defect structure of quartz is a fingerprint of its conditions of formation. A knowledge of the interrelation between quartz genesis and the specific properties developed at that time can be used both for the reconstruction of geological processes and for specific technical applications. Selected examples in the present study give an overview of how to analyse and use the specific information inherent in the mineral quartz.