Abstract. Enargite (Cu3AsS4) and tennantite
(Cu12As4S13) are typical As-bearing sulfides in intermediate-
and high-sulfidation epithermal deposits. Trace and major element variations
in enargite and tennantite and their substitution mechanisms are widely
described. However, Raman spectra of the minerals with correlative
quantitative chemical information are rarely documented, especially for
enargite. Therefore, comparative electron and μ-Raman microprobe
analyses were performed on enargite and fahlore grains. These spectra can be
used in the industrial detection and subsequent removal of As-bearing sulfides
prior to ore beneficiation in order to diminish the environmental impact of
the metallurgical technologies. A simple Sb5+–As5+ substitution in enargite was confirmed by Raman
analyses. Similarly, a complete solid solution series from tetrahedrite to
tennantite (i.e., Sb3+–As3+ substitution) can be correlated with a
gradual evolution in their Raman spectra. In turn, Te4+ occupies the
As3+ and Sb3+ sites in fahlore by the coupled substitution
Te4+ + Cu+ → (As, Sb)3+ + (Cu, Fe, Zn)2+.
Accordingly, Raman bands of goldfieldite (Te-rich member) are strongly
broadened compared with those of tetrahedrite and tennantite. A secondary phase with high porosity and a fibrous or wormlike texture was
found in enargite in a weathered sample. The chemical composition, Raman
spectrum, and X-ray diffraction signature of the secondary phase resemble
tennantite. A gradual transformation of the primary enargite into this
secondary phase was visualized by comparative electron and Raman microprobe
mapping.