Abstract:

In this study we observe the microstructure of sheet and flake pyrite crystals systematically using the transmission electron microscope (TEM) and we discover that numerous pyrite morphologies such as square and rectangle etc can be formed under hydrothermal conditions. Pyrite sheet and flake crystals grow perfectly and have few internal defects. Our measurement indicates that most quadrilateral pyrite crystals have two sets of edges parallel to (010) and (100), and the growth crystal face is (001); and a few quadrilateral pyrite crystals have two sets of edges parallel to (010) and (101), and the growth crystal face is (101). The long axis of rectangular flake crystals growth direction is <001>. We hold that pyrite crystals have multiple morphologies, most sheet and flake crystals grow along the twodimensional growth plane (001), and extend along the <001> direction to constitute the twodimensional crystals.

Key words: hydrothermal method, flake pyrite, microstructure, growth plane, growth direction