Ojuela mine, The

The Ojuela mine specimens studied by Kampf et al. (1984) contain more Mn than Zn; Brugger et al. (2002) have recently redefined the components of the Iotharmeyerite subgroup, with the result that analyses showing more Mn than Zn are now referred to the new species name manganlotharmeyerite. Therefore, the Ojuela mine specimens studied by Kampf et al. (1984) are now redefined as manganlotharmeyerite. Although these represent the first-ana-lyzed and reported examples of what has been defined as the new species, Ojuela is not considered the type locality because all analyses in the recent redefinition are based on specimens from the Starlera Mn mine in the Swiss Alps. Manganlotharmeyerite is brittle with an irregular fracture and distinct cleavage parallel to (001); it is transparent to translucent, with an adamantine luster and a brown-red to dark red-orange color.

Mapimite Zn^sub 2^Fe^sup 3+^^sub 3^(AsO^sub 4^)^sub 3^(OH)^sub 4^ [middot] 10H^sub 2^O

In the legrandite zone in Palomes Oriente, early in the 1970's, pale green tabular crystals to 4 mm of a then-unknown species resembling torbernite (later described as mapimite) were found with needles of another unknown species (later described as ojuelaite), sparsely spotting a few pieces of gossan matrix. Nearly all of these crystals were destroyed during inconclusive testing, so the formal description of both species had to wait for a later find (Mike New, personal communication, 2002).

Mapimite and ojuelaite were formally described from the Ojuela mine by Cesbron et al. (1981), from specimens found in the late 1970's in Palomas Oriente-San Carlos. In this occurrence, mapimite formed crystals to 3 mm in vugs in goethite, associated with adamite, scorodite, ojuelaite, paradamite and smithsonite. The monoclinic, flattened mapimite crystals are strongly trichroic, blue to greenish blue to green. The habit is square platelets flattened on {001} and bounded by the prism faces {110); a beveling face on one edge {111} is rarely present. Good cleavage is present on (001} and {010}, and the crystals arc polysynthetically twinned on {001} with a [104] pseudoaxis. The Ojuela mine is currently the only known locality for the species.

Marcasite FeS^sub 2^

Marcasite is common in the primary ores of the district, frequently replacing pyrrhotite and enargitc. In the Ojuela mine, intergrowths of pyrite and marcasite replace pyrrhotite in the sulfide ores of Monterrey (Hoffmann, 1967).

"Mazapilite"

"Mazapilite" was described as a species in 1889, and at first (his name was applied to some sharp brown crystals found in 1927 by Foshag near the town of Ojuela, in an assemblage with carminite, scoroditc, dussertite and arseniosideritc. But Foshag (1937) found the crystals to be arseniosiderite pseudomorphs after scorodite, and the species "mazapilite" is now discredited (Bayliss, 2000).

Melanterite Fe^sub 2^+SO^sub 4^[middot]7H^sub 2^O

Pale green to bluish green melanterite occurs with chalcanthite along fault-gouge and fracture zones, frequently mixed with goethite (Hoffmann, 1967).