Fig. 6. Scanning electron micrographs of representative weathered pyrite particles separated from the overburden following 378 d of incubation and initially containing 4.1% FeS₂. (A) Weathered pyrite particle from the 25% acid–base account deficit treatment. (B) Weathered pyrite particle from the 0% acid–base account deficit treatment. (C) Large weathered pyrite particle from the 25% acid–base account deficit treatment. (D) Large pyrite particle from the 125% acid–base account deficit treatment. There is no apparent evidence of pitting and the morphology is similar to pyrite particles at time zero.