Hydrated normal sulphate
Specific gravity: 2.23
Colour: Blue, colourless, white, yellow, light green, grey, colourless in transmitted light
Solubility: Slowly soluble in water, easily soluble in acids
Common impurities: As
Rhomboclase is an uncommon secondary mineral formed by
alteration of pyrite, marcasite or
pyrrhotite, especially in an arid climate; it is typically of post-mining
origin. Associated minerals include szomolnokite,
chalcanthite and pyrite
At the Socavon mine, Oruro City, Cercado Province, Oruro, Bolivia, rhomboclase occurs as thin platy crystals up to 2 cm in size with melanterite and copiapite (Dana).
At the Alcaparrosa Mine, Sierra Gorda, Antofagasta Province, Antofagasta, Chile, colourless and faintly brownish-purple rhomboclase and intimately associated szomolnokite and römerite with bright angular pieces of pyrite scattered through the minerals (AM 23.669-760).
At the type locality, Smolník, Gelnica District, Košice Region, Slovakia, rhomboclase occurs in an altering pyritic ore body, associated with szomolnokite and copiapite (Mindat).
Back to Minerals