The chemical formula of mineral Meta-Torbernite is indicated by Cu(UO2)2(PO4)2 – 6-8H2O or Hydrated Copper Uranyl Phosphate. Meta-Torbernite is actually a Phosphate mineral. Meta-Torbernite is considered as a very minor ore of uranium. It is also most commonly used as mineral specimen and is often found exhibiting nice and splendid microscope appearance when viewed with the aid of petrographic polarizing light microscope used in the field of optical mineralogy. Meta-Torbernite is actually a dehydration product mineral Torbernite. Torbernite converts to Meta-Torbernite when it losses water. Thus, it undergoes the process called pseudomorphism. In optical mineralogy, a pseudomorph is generally an atom by atom replacement of one mineral’s chemistry in replacement of another. It should be noted that the outward appearance remain largely unchanged. The process is then leaving the crystal shape of the original mineral intact, but the original mineral is no longer there. Pseudomorph means false shape. It was named with the meta prefix to indicate a lower hydration level and its relationship to mineral Torbernite. The first specimen was first discovered at Saxony, Germany in 1786.
Mineral Meta-Torbernite is most commonly found in various shades of pale to dark green to almost black color, which could actually appear more splendidly wonderful when viewed with the aid of petrographic polarizing light microscopes used in the field of optical mineralogy. It is also usually found showing vitreous to dull luster when viewed with the aid of polarizing microscope for mineralogists. Most crystals of Meta-Torbernite are usually found translucent to opaque in appearance. Meta-Torbernite is known to crystallize in the tetragonal system of crystal formation. In the field of optical mineralogy, this tetragonal system comprises crystals having three axes, which are all in a position perpendicular to one another. Two axes are usually found having the same or equal length.
The crystal habit of mineral Meta-Torbernite as described in the field of optical mineralogy includes tabular square crystals dominated by two pinacoid faces. Meta-Torbernite crystals can form in parallel growths giving a stacked book kind of look. It can be also found as crust, micaceous, foliated and scaly aggregates. It is important to note that all Meta-Torbernite crystals are pseudomorphs of Torbernite. Meta-Torbernite is most commonly found showing perfect cleavage in one direction, which can be seen more clearly visible when viewed with the aid of polarized light microscopes. The fracture shown by Meta-Torbernite when it is viewed under polarized microscope is usually uneven. The hardness measure of the mineral when it is evaluated using the Mohs scale method is usually 2.5. Meta-Torbernite is most commonly found leaving a pale green streak when specimen is rubbed on a white porcelain streak plate. The specific gravity measure of the mineral Meta-Torbernite is approximately 3.7, which is considered above average for translucent minerals. It is also important to note that Meta-Torbernite is a radioactive mineral and it should be stored away from other minerals that are affected by radioactivity and human exposure should be limited. The cleavage sheets of Meta-Torbernite are also surprisingly brittle. It may also exhibit anomalous interference colors when viewed between crossed nicols of polarized microscopes used in the field of optical mineralogy. It also exhibits a moderate surface relief when viewed under several adjustments on the aperture diaphragm of the petrographic polarizing microscope for mineralogists. It also shows extreme dispersion when viewed under polarized microscopes for mineralogists. Meta-Torbernite is most commonly found showing weak pleochroism under polarizing microscope used in optical mineralogy. Meta-Torbernite is usually found showing uniaxial figure sometimes optically positive and sometimes negative. But it should also be noted that it has anomalously biaxial sector. Meta-Torbernite is most commonly found associated with autunite, uranocircite, torbernite, uranophane, uraninite, and other uranium minerals. The best field indicators of Meta-Torbernite include color, non-fluorescence, and crystal habit, higher density than torbernite, radioactivity, associations, and brittle cleavage sheets. Meta-Torbernite is actually a secondary mineral in weathering uranium-bearing deposits. Meta-Torbernite notably occurs at several localities including England, Canada, Zaire, Germany, and France.
