The Mineral VAUXITE

  • Chemistry: FeAl2(PO4)2(OH)2 - 6H2O, Hydrated Iron Aluminum Phosphate Hydroxide.
  • Class: Phosphates
  • Uses: Only as mineral specimens.
  • Specimens

Vauxite is an unusual blue-colored iron mineral. As a coloring agent in minerals, iron can produce any color in the rainbow but commonly produces reds, yellows and browns. Especially common is the red to yellow color of rust, limonite, powdered hematite and other iron oxides. This misleads many people to believe that iron can only produce these colors. But in vauxite's blue, amethyst's purple, ludlamite's apple green and other examples; this myth about iron's coloring abilities can be dispelled.

Vauxite is closely related to the often associated mineral paravauxite. Paravauxite appears to be different from vauxite only in the number of water molecules in the structure. But the presence of these water molecules alters the structure to the point that paravauxite has perfect cleavage while in sharp contrast, vauxite has no cleavage. The only other significant differences include paravauxite's green to colorless color verses vauxite's blue color.

Vauxite, paravauxite and metavauxite (a polymorph of paravauxite) are all found at the famous tin oxide deposits at Llallagua, Potosi, Bolivia. All are associated with the primary tin ore, cassiterite. They form as a result of precipitation from hydrothermal solutions.

PHYSICAL CHARACTERISTICS:

  • Color is pale to dark blue.
  • Luster is vitreous.
  • Transparency: Specimens are translucent to transparent.
  • Crystal System is triclinic.
  • Crystal Habits include tabular crystals and radiating fibrous clusters.
  • Cleavage is absent.
  • Fracture is conchoidal.
  • Hardness is 3.5
  • Specific Gravity is approximately 2.4 (average).
  • Streak is white.
  • Associated Minerals include cassiterite, metavauxite, paravauxite, wavellite, quartz and limonite.
  • Notable Occurrences are limited to the famous tin deposits at Llallagua, Potosi, Bolivia and a few minor localities around the world.
  • Best Field Indicators are color, locality, crystal habit, associations and lack of cleavage.
VAUXITE specimens:
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VAUXITE specimen vau-1
$ 50.00
Dims: 3.2 x 2.1 x 0.7" (8.1 x 5.3 x 1.8 cm)
Wt: 2.45 oz. (69.7 g)
Mina Siglo Veinte, Llallagua, Bolivia
This hand specimen consists of several very small, crystalline masses of Vauxite that rest on a flat, gray base rock. These masses appear to be made out of countless, nearly microscopic Vauxite crystals that are a bit too small to effectively study with a loupe. All have a pale blue color and a dull waxy-to-pearly luster, and are translucent. These masses rest on what are likely crystals of white metavauxite or paravauxite which occur as definite triclinic blades and are colorless and dimly transparent.
no photo
vau-1 ($ 50.00)
Mina Siglo Veinte, Llallagua, Bolivia
VAUXITE specimen vau-2
$ 108.00
Dims: 1.0 x 1.0 x 0.5" (2.6 x 2.5 x 1.3 cm)
Wt: 12 g w/ specimen box
Huanuni Mine, Oruro Department, Bolivia
This interesting thumbnail specimen consists of a partial Vauxite crust. The crust is made up of scores of tiny clusters of aggregated or perhaps radiating Vauxite tablets that are intergrown so as to create seemingly botryoidal formations. The crystals therein are so tiny that it is very difficult to study them with a loupe, and they are so tightly aggregated that individual crystals are not easily isolated. However, they appear to be in good condition. The crust has a moderate blue coloration with a hint of gray and shows a dull pearly luster. It is translucent along its edges, so individual crystals are likely transparent to a degree. There is no base rock present, and the piece is hot-glued inside a plastic thumbnail box.
no photo
vau-2 ($108.00)
Huanuni Mine, Oruro Department, Bolivia
VAUXITE specimen vau-3
$ 60.00
Dims: 1.69x1.02x0.31" (4.3x2.6x0.8cm)
Wt: 22.2ct (4.44g)
LLallagua, Bustillo, Potosi, Bolivia
This specimen of vauxite is from its type locality. The host rock looks like a thin shell of quartz, coated with a thin layer of pale vauxite crystals. If it weren't for the pale blue color, I would have suspected that these crystals were paravauxite. Actually, the vauxite appears to be coated with more of this mineral, a sparkly druze of square prismatic crystals with a slanted termination. The bulk of the vauxite is in the form of masses of lovely blue crystals whose form cannot be identified (all of the identifiable crystals appear colorless).
no photo
vau-3 ($ 60.00)
LLallagua, Bustillo, Potosi, Bolivia
 

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