ZONATION OF FORM AND COMPOSITION OF PYRITE CRYSTALS OF THE BEREZOVSKY GOLD DEPOSIT (URALS)

Abstract

Morphology, zonation and composition of pyrite crystals from quartz veins, beresites and listvenites of the Berezovsky gold deposit are examined. During the crystallization, the pyrite forms changed following a relatively simple scheme {111} → {111}+{100} → {100} → {100}+{210} or more complex schemes {100} → {210}+{100} → {100} → {100}+{111} → {100} → {100}+{210}, {100} → {100}+{111} → {100}+{421} → {100} → {100}+{210} and others. The earliest forms of growth zones of pyrite crystals are characteristic of deeper horizons. The sulfidequartz veins were formed under active tectonic conditions, which are manifested in deformation of pyrite and healing cracks by later zones. In the course of the opening of new cracks, the early pyrite forms of sulfide-quartz veins were upgraded up to polyhedra in the fractures (veins) and also replaced beresite. The {210} peripheral zones of pyrite crystals are enriched in heavy S isotope (dS34 from +8.5 to +10 ‰) and often contain microinclusions of other minerals, including gold. The LA-ICP-MS trace element patterns of the (100) cross section of one druzy pyrite crystal 11 mm in size from a sulfide-quartz vein also reflect the complex evolution of its formation. Along with more common muscovite, fluorapatite and galena, the microinclusions of zircon, monazite-(Ce) and brannerite UTi2 O6 were first identified in pyrite of the deposit.

Keywords

• pyrite
• crystals morphology
• zonation of composition
• mineral inclusions
• berezovsky deposit
• ural