Surface nanoscale relief of mineral crystals and its relation to nonautonomous phase formation

The features of the nanoscale relief of crystals formed under natural and experimental conditions are considered by examples of pyrite, sphalerite and its solid solutions, and native gold. Nonautonomous phases (NAPs), which differ from the bulk mineral by their chemical composition, stoichiometry, and structure, are fixed within an approximately half-micron surface layer. For pyrite crystals, the NAP composition and morphology vary depending on the genetic conditions. In the case of sphalerite, hierarchical fractal structures arise on the crystal surface due to the formation of NAPs of sulfate or sulfoxide composition. An increased content of admixed elements (Cd, Hg) is observed on the surface at the largest NAP development. Gold sulfide NAPs are observed to be stable at a relatively high temperature under hydrothermal conditions.