Images
Formula: Fe3+2(SO4)3.11H2O
Hydrated normal sulphate
Crystal System: Triclinic
Specific gravity: 2.11 to 2.15 measured, 2.14 calculated
Hardness: 2½
Streak: White
Colour: White to very pale violet to red-violet; colourless to pale rose in transmitted light
Solubility: Easily soluble in water.
Environments
Quenstedtite is an uncommon mineral formed in the oxidised zone of
pyrite-rich mineral deposits, especially in arid regions. Associated minerals
include coquimbite, copiapite and
römerite
(HOM).
Localities
At the Alcaparrosa Mine, Sierra Gorda, Antofagasta Province, Antofagasta, Chile, quenstedtite was intimately
associated with coquimbite and
rostite. In association with
coquimbite it shows a remarkable case of replacement by alteration. Most of
the quenstedtite is altered to coquimbite. Apparently the latter
mineral forms earlier than quenstedtite but, due to the strong overlapping of their stability fields, both can
form at essentially the same time. Within the range of the overlapping fields the quenstedtite alters readily to
coquimbite through the loss of one molecule of water. Unaltered material
occurs as crystal druses in the coquimbite and in rounded aggregates of
minute crystals in copiapite
(AM 23.739).
The type locality is Tierra Amarilla, Copiapó Province, Atacama, Chile.
Back to Minerals