Understanding the surfaces and crystal growth of pyrite FeS2

Abstract

Pyrite is a common sulfide mineral, which has arisen early interest by its euhedral shape and by its metallic glow similar to gold. However, it is only in our century that we began to understand pyrite crystal growth, considering the thermodynamic and kinetic aspects of crystal formation as a function of temperature and concentration of the elements present in the medium. This article reports an analysis by molecular mechanics of 11 surfaces associated to observed morphologies in order to explain the growth of natural and synthesized minerals. The lowest surface and attachment energies (respectively 1.04 J/m2 and -20.3 kJ/mol) were obtained for the (001) plane, indicating that it is the most stable surface and that kinetic growth also preferentially occurs on this plane. Less known properties, such as crystal striations along the <100> directions, are also discussed.