Minerals don't come much simpler than molybdenite, MoS2. It consists of paired triangular sheets of sulfur atoms with molybdenum between. The Mo-S coordination polyhedron is a triangular prism. The sheets are not strongly bonded but are held together by weak Van der Waals forces. The weak inter-sheet bonding accounts for the softness and slipperiness of molybdenite. Although molybdenite can be confused with graphite, it doesn't leave a mark on paper. Also, graphite has a dull, dark neutral gray color, whereas molybdenite usually has a much brighter luster and a bluish-purple cast.
Above: oblique view of the molybdenite structure
Above, view perpendicular to the layers, showing the relationship between layers.
Created 22 April 2013, Last Update 05 Jun 2013
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