The chemical formula of mineral Thorite is indicated by (Th, U)SiO4 or Thorium Uranium Silicate. Thorite is actually a Silicate mineral. It is considered as a minor ore of thorium and uranium. It is also most commonly used as mineral specimen and it is often found exhibiting nice and interesting microscope images when viewed with the aid of polarizing microscope used in the field of optical mineralogy. Thorite is the most common thorium mineral. As studied by most scientists, thorium is a highly radioactive element and it can be actually used as a replacement for uranium in nuclear power generation. Thorite is currently considered as an important ore of uranium. Thorite has many varieties known in the mineral world. Among this is uranothorite, which s particularly rich in uranium and it has been also a viable uranium ore at Bancroft, Ontario, Canada. Other varieties include orangite, an orange variety and also calciothorite, an impure variety with trace amounts of calcium.
Thorite has a closely related variety called Thorogummite, which is said to be a product of alteration of Thorite. Thorite is also related to a mineral called huttonite. Huttonite and Thorite are dimorphs. In the field of optical mineralogy, this means that the minerals have the same chemistry but they have different structures. Specimens are often metamict because thorite is highly radioactive. This condition of radioactive minerals results from the destructive effects of its own radiation on its crystal lattice. The effect can actually destroy a crystal lattice completely while leaving the outward appearance unchanged. The hydration of the structure can occur during this process and a new mineral is formed called Thorogummite.
Specimens of Thorite are generally found in igneous pegmatites and volcanic extrusive rocks, hydrothermal veins and contact metamorphic rocks as well as small grains found in detrital sands. Thorite crystals are rare but when found they can actually produce nicely shaped short prismatic crystals with pyramidal terminations. This can be seen more splendidly exhibited when viewed under polarized microscopes for mineralogists. It is important to note that Thorite is a radioactive mineral and therefore it must be stored away from other minerals that are subject to damage from radioactivity and of course human exposure should be limited.
Mineral Thorite is normally found black in color, but also brownish black, orange, yellowish-orange and dark green which can be found more interesting when viewed with the aid of petrographic polarizing light microscopes for mineralogists. Thorite is also found showing resinous luster when viewed in reflected light of polarized microscope used in optical mineralogy. Most crystals of mineral Thorite are found opaque in appearance. It is also known to crystallize in the tetragonal system of crystal formation. In 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 habits of mineral Thorite as described in the field of optical mineralogy usually include short prismatic crystals with a square cross-section and simple pyramidal terminations. It is also found massive, embedded irregular grains and reniform. Thorite is most commonly found showing poor cleavage in two directions, but this is rarely seen. Thorite is also most commonly found showing conchoidal fracture when specimen is evaluated with the aid of polarizing microscope for mineralogists. The hardness measure of Thorite when it is evaluated using the Mohs scale method is usually 4.5 to 5. Thorite is also most commonly found leaving an orange to brown streak when specimen sample is evaluated with the aid of polarizing microscopes. The specific gravity measure of mineral Thorite is 4.1 to near 7 grams per cubic centimeters. Thorite is nearly always metamict and always strongly radioactive mineral. Thorite is usually found associated with other interesting minerals including betafite, quartz, biotite and feldspars. The best field indicators of mineral Thorite usually include fracture, color, radioactivity, luster and crystal habit. Thorite notably occurs at several localities including Norway, Ontario in Canada, Arizona in USA and also in Germany.
