The Mineral Allophane
allophane Picture

Allophane, is more of an amorphous to crystalline mineraloid form of crystalline or Amorphous Hydrous Silicate of aluminium than a mineral per se. It is best identified by its distinct infrared spectrum and X-ray diffraction pattern. It was in 1816, in Germany, that Allophane was first described. Having a pH value of 5-7, the clay-like Allophane more or less thrived only in a mildly acidic environment. It has an amorphous crystal structure and waxy luster. The color of Allophane may vary from white, green, brown to blue.

Chemical Formula

Al2O3· (SiO2) 1.3-2· (2.5-3) H2O

Derivation Of Name

Allopane is  a Greek word. In Greek, “Allos”means other and “Phanos” means to appear, meaning,  this mineral gives a deceptive reaction when it tested in a blowpipe flame.

Occurrence

The Allophane mineral is a hydrothermal alteration product of “weathering, ” resulting from the breakdown of mineral, soil and rock (feldspars and volcanic glass)  in a condition of  no movement or “in situ”, and is best not confused with erosion.

Gemology

The gemstone of this rare mineraloid varies from light to dark hues. Colorful specimen exist of bright blue Azurite inter-grown with translucent green. Amazonite is a popular collector’s item and also used in jewelry It is usually light green to blue- green and is found in granite and pegmatites.

Source

The major source of Allophane mineral is in Germany, at the mines of the Rieche, Saxony and Himmelfahrt, and in  the districts of Freiberg and Erzgebirge

Mineralogy

It is the main member of "Allophane Group." In aqueous conditions, it can be altered  to form Halloysite and in  desilicating conditions,  it can form Gibbsite. It also contains a variety of Cupro-Allophane.

Color White, brown, green, yellowish blue to sky-blue.

Density 3 g/cm3

Hardness: 5 to 6 on the Mohs Scale.

Main Applications

Allophane’s low cost,  combined with its environmentally friendly features renders it as a highly sought after product used in the remediation process of both  phosphorous rich water effluent and euphoric waters.    

The Mythical

This stone is said to promote balance, enhance stability and sociability skills. It is also known for protecting the eyes and glands.

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