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Click Here For Best Selection Of High Quality Polarizing Microscope

Click Here For Best Selection Of High Quality Polarizing Microscope

The chemical formula of mineral Carnallite is indicated by KMgCl3-6H2O or Hydrated Potassium Magnesium Chloride. Carnallite is actually a Halide mineral. Mineral Carnallite was actually first discovered in the year 1856 at the Strassfurt Deposit in the Saxony, Germany. Carnallite mineral species was actually named after Rudolf von Carnall (1804-1874), a Prussian mining engineer. Carnallite is known to crystallize in the orthorhombic system. In optical mineralogy, this orthorhombic crystal system comprises crystals having three mutually perpendicular axes, of which all are of different lengths.


            Carnallite is most commonly found white, colorless or yellow color and it is more splendidly exhibited under petrographic polarizing microscope. It has been described in optical mineralogy that the colorless mineral sections of Carnallite allow the whole constituent of the white light to pass through making the mineral non-pleochroic even between crossed nicols of polarizing light microscope for mineralogists. Carnallite  is rarely found exhibiting a blue color. If Carnallite is found with hematite inclusion, the mineral specimen can be found showing reddish color when viewed closely with the aid of petrographic polarizing microscopes. Carnallite is usually found exhibiting a vitreous to greasy luster and sometimes resinous to dull when viewed in reflected light of petrographic polarizing light microscope. Mineral Carnallite commonly displays an absent cleavage under a polarizing microscope used in optical mineralogy. Carnallite is usually found showing a conchoidal fracture when it is closely evaluated under a petrographic polarizing light microscope. The specific gravity measure of mineral Carnallite usually gives an approximate value of 1.6 grams per cubic centimeters, which is commonly considered light even for translucent minerals. The hardness measure of mineral Carnallite when it is evaluated using the Mohs scale method is usually found 2.5. Carnallite is most commonly found leaving a white streak when it is rubbed on a white porcelain streak plate.


            Carnallite mineral crystals are usually found transparent to translucent in appearance. The crystal habits of Carnallite as described in optical mineralogy usually include granular and massive forms, which are usually interesting to view under a polarizing microscope. These are also the common textures that are observed in granite and other interesting igneous rocks. Rare individual crystals are usually found as pseudo-hexagonal and sometimes tabular. In optical mineralogy, the tabular crystals are usually found in shape like a book when viewed closely under petrographic polarizing microscope. The pseudo-hexagonal crystals on the other hand are usually showing a hexagonal outline.  Sometimes they may be also found in fibrous form that commonly exhibits interesting and fascinating image under polarized light microscopes used in optical mineralogy.


            Carnallite commonly shows a moderate surface relief when it is evaluated with the aid of a petrographic polarizing light microscope. Carnallite minerals are also fluorescent in either short or long wave ultraviolet light. Specimens of Carnallite are actually found showing a biaxial positive figure when closely evaluated under petrographic polarizing light microscope. Carnallite has no dispersion display in transmitted light of polarized light microscope for geologists. Mineral Carnallite has a barely detectable radioactivity. The refractive indices of Carnallite are usually found ranging from 1.467 to 1.494. Carnallite may also show a polysynthetic twinning that can be seen more clearly visible when the section is viewed closely under petrographic polarizing light microscope. The maximum birefringence is found to be 0.027. Mineral specimen. There is no specific data on the toxicity and health dangers for mineral Carnallite. However, the specimens of Carnallite should be treated with great care and use of sensible precaution is advised upon handling them.


Carnallite mineral crystals commonly form in marine evaporite deposits wherein the seawater has been concentrated and are commonly exposed to prolonged evaporation. Mineral Carnallite also forms precipitates with several other interesting potassium and magnesium evaporate minerals like kieserite, sylvite, picromerite, kainite and polyhalite. Carnallite minerals can be also found in massive beds form but these crystals are actually considerably rare in occurrence. Carnallite crystals undergo a process called deliquescence where unfortunately absorb water from humid air. But storing the Carnallite specimens accordingly in sealed and dry containers can ease this process.


            The best field indicators of Carnallite minerals usually include lack of cleavage, fracture, density, taste, environment of formation, deliquescence and its wonderful association with other interesting minerals. Carnallite minerals are commonly formed in the marine evaporates. Carnallite is also considered as a rare double chloride mineral, which only forms under specific environmental conditions in an evaporating sea or sedimentary basin. It also occurs as an alteration product of pre-existing salts. Carnallite minerals also notably occur at some types of localities including Western Texas in the United States, Iran, Mali, Spain and Ukraine as well as Tunisia. Potassium and magnesium salt deposits are most notably found in the Paradox Basin in Colorado and Utah, also in the Carlsbad in New Mexico, the deposits in Strassfurt in Germany as well as the Williston Basin in Saskatchewan in Canada and the Perm Basin in Russia.

Monday, September 29th, 2008 at 2:41 am
The Halides Mineral Class
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Click Here For Best Selection Of High Quality Polarizing Microscope