Secondary crusts in humid tunnels in oxidized portions of sulfide deposits in aluminous rocks; apparently deposited directly from mine water at about 27 deg C and 100% humidity.
IMA Status:
Approved IMA 1976
Locality:
San Manuel mine, Mammoth district, Pinal Co., Arizona, USA. Link to MinDat.org Location Data.
Name Origin:
Named for Joseph John Urban (1915-1997), Tucson, Arizona, USA, mineral collector who first observed the natural material.
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Sabelli C , Zeitschrift fur Kristallographie , 173 (1985) p.33-39, Refinement of the crystal structure of jurbanite, Al(SO4)(OH)*5H2O, Locality: Cetine mine, Tuscany, Italy
Physical Properties of Jurbanite
Cleavage:
None
Color:
Colorless.
Density:
1.786
Diaphaneity:
Transparent
Fracture:
Brittle - Generally displayed by glasses and most non-metallic minerals.
Hardness:
2.5 - Finger Nail
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Jurbanite
Gladstone-Dale:
CI meas= -0.04 (Good) - where the CI = (1-KPDmeas/KC) CI calc= -0.015 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2577,KPDmeas= 0.2641,KC= 0.2538 Ncalc = 1.45 - 1.46