Weathering of phlogopite in simulated bioleaching solutions

►Phlogopite was extensively weathered in iron-oxidizing bacterial cultures. ►Phlogopite was altered to a mixed layer structure including expansible vermiculite. ►Release of interlayer-K from phlogopite was coupled with K-jarosite precipitation. ►NH4+ and K+ (100 mM) effectively prevented the structural alteration of phlogopite. ►Phlogopite was not structurally altered in sulfur-grown bacterial cultures.