Antofagasta is located within the Atacama desert, home to other minerals that occur in extremely arid
environments, such as beautiful deep green atacamite, and, in the animal
kingdom, the guanaco with its gentle nature
and long-lashed eyes.
Images
Formula: Na2Ca(SO4)2.1.5H2O
Hydrated sulphate
Crystal System: Monoclinic
Specific gravity: 2.42 measured, 2.465 calculated
Hardness: 3
Streak: White
Colour: Colourless
Luminescence: Not fluorescent under UV
Environments
Hydrothermal environments
Fumeroles
Localities
At the type locality, the Coronel Manuel Rodríguez mine, Mejillones peninsula, Mejillones, Antofagasta Province,
Antofagasta, Chile, antofagastaite was found in the oxidation zone of sulphide –
quartz veins in the extremely arid climate. Associated minerals include
sideronatrite,
metasideronatrite,
aubertite, gypsum,
ferrinatrite, glauberite,
amarillite and an unidentified
iron phosphate. Antofagastaite occurs as transparent, colourless,
vitreous prismatic crystals up to 0.5 × 1 × 5 mm3, typically combined in open-work aggregates up to
1 cm across
(MM 83.6.781-790).
At the Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik Volcanic
field, Milkovsky District, Kamchatka Krai, Russia, antofagastaite occurs together with
syngenite and blödite
(MM 83.6.781-790).
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