The product of the reaction is the hydrous iron sulfate in two crystalline modifications: FeS[O.sub.4] x 7[H.sub.2]O (
melanterite) and FeS[O.sub.4] x 4[H.sub.2]O (rozenite).
Interesting occurrences of secondary sulfates such as
melanterite, gypsum and epsomite have also been reported.
Mineral matter can also contain smaller amounts of gypsum (CaS[O.sub.4]?2H2O),
melanterite (FeS[O.sub.4]?7H2O), and other sulfur-containing minerals.
The iron sulfate
melanterite is found as colorless, water-soluble fibers; blue copper sulfate chalcanthite lamellae and blue-green aggregates of acicular crystals of the Ca-Cu-Zn sulfate serpierite (some accompanied by green spherules of cornwallite) are found at Aghbar.
Masses of beautiful blue crystals of post-mining chalcanthite are found in several sections of the mine, especially along the San Jose vein, growing in fissures in the rock walls or hanging from wooden beams, and these are popular with local mineral collectors, although many of their specimens of calcantita are really the more common cuprian
melanterite.
Associated minerals include botryogen, copiapite, anhydrite, gypsum,
melanterite, marcasite and sulfur.
Other minor associated minerals include kalinite, mirabilite, alunogen, pickeringite and
melanterite. Several blue and orange-colored sulfates have not been positively identified but probably include romerite, voltaite, metavoltine and chalcanthite.
Associated minerals are:
melanterite, pickeringite, potassium alum, jarosite, gypsum, arsenolite, sulphur and some unknown minerals.
Associated minerals are: coskrenite-(Ce), zugshunstite-(Ce),
melanterite, halotrichite, pickeringite, apjohnite, epsomite and other hydrated sulfates.
A relatively rare secondary mineral, botryogen occurs as thin, orange-yellow crusts up to several square centimeters in area in the Andrassy III section, associated with epsomite,
melanterite and copiapite (Szakall et al., 1997).
Greenish brown
melanterite has been found as an alteration product of iron sulfides in the Brenner mine.