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Formula: CaCu10(Te4+O3)4(As5+O4)4(OH)2.4H2O
Tellurite, arsenic-bearing mineral
Crystal System: Triclinic
Specific gravity: 4.50 calculated
Hardness: 3 to 4
Streak: Pale green
Colour: Emerald-green to pale green
Luminescence: nonfluorescent under
both long-and short-wave ultraviolet light
Environments
Localities
At the type locality, the Centennial Eureka Mine, Eureka, Tintic Mining District, Juab County, Utah, USA,
juabite has been identified on only a single specimen collected from the dumps. It is extremely rare; on the
holotype specimen, which measures 14 x 10 x 8 mm3, it is confined to one area of the specimen where it is
found as platy masses in three adjacent drusy quartz-lined cavities that are
approximately 1 mm long by less than 0.5 mm wide. Associated minerals are black metallic
enargite (with which it is intimately associated),
beudantite (as a mustard yellow crystalline crust) and an ill-defined
mineral (as a green-yellow opaque crystalline crust). It is
believed that juabite formed from the breakdown and partial replacement of
enargite by tellurium-enriched
fluids.
Additional copper- and
tellurium- bearing
secondary minerals that have been identified on similar
specimens from the Centennial Eureka mine dumps include mcalpineite,
frankhawthorneite,
jensenite, leisingite,
utahite, xocomecatlite,
cesbronite, dugganite and
quetzalcoatlite.
Juabite occurs as crystalline subhedral platy masses that are up to 0.3 mm in longest dimension. Platy
euhedral crystals are relatively scarce. Individual plates average 125 x 100 x 1-2 microns3 in size.
Juabite masses are gemmy emerald-green; thin crystals are a very much lighter green. The lustre is vitreous
to adamantine on cleavage faces, and the mineral is translucent in masses to transparent in thin plates
(MM 61.139-144).
Juabite has also been found on specimens from two other mines in the Tintic district, the Gold Chain mine and
the North Star mine. An interesting and unique property of juabite among Tintic minerals is that it can
exhibit dichroism, appearing emerald-green down one axis and deep blue down another
(MinRec 55.2.207-208)
Juabite from the Centennial Eureka Mine -
Image
Juabite from the North Star Mine - Image
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