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Click Here For Best Selection Of High Quality Polarizing Microscope

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The chemical formula of mineral Phosgenite is indicated by Pb2CO3Cl2 or Lead Carbonate Chloride. Phosgenite is actually a Carbonate mineral. It is most commonly used as mineral specimen and could appear more interesting when evaluated under polarizing microscope used in optical mineralogy. Mineral Phosgenite is a relatively rare carbonate that shows rare symmetry, tetragonal. The high luster exhibited by the mineral in reflected light of petrographic polarizing microscope is usually due to its lead content. It is interesting to note that mineral Phosgenite has been found in the slug dump of the ancient Greeks at Mediterranean Sea. The lead rich rocks have reacted with sea water over time and form Phosgenite crystals.

             Mineral Phosgenite is most commonly found colorless, white, brown to yellow in color which could appear more interesting when viewed with the aid of polarizing microscopes used in optical mineralogy. Phosgenite is also most commonly found showing adamantine to greasy luster when viewed in reflected light of petrographic polarizing microscope for mineralogists. Most crystals of mineral Phosgenite are found transparent to translucent in appearance. The crystal habit of mineral Phosgenite as described in optical mineralogy generally includes crystals that are long slender prismatic to acicular with either a pinacoid, a tetragonal trapezohedral or a pyramidal termination that tappers due to multiple secondary pyramidal faces. Phosgenite can also be found stubby, tabular, massive and granular. It is however important to note that large crystals are weakly striated lengthwise as can be noticed when specimen it viewed closely under polarized microscope. Phosgenite is 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. Mineral Phosgenite is most commonly found showing good prismatic cleavage in two directions lengthwise and poor basal cleavage when specimen is closely viewed under petrographic polarizing microscope used in optical mineralogy. The hardness measure of mineral Phosgenite when it is evaluated using the Mohs scale method is usually 2  to 3, wherein 2.5 hardness will scratch a prism face parallel to the long axis, but not across it. Phosgenite is also known to show fluorescent bright yellow in ultra violet light. This characteristic of Phosgenite adds up to its desirability as a collection piece among collectors. The specific gravity measure of mineral Phosgenite is most commonly found 6+grams per cubic centimeters, which is heavy for translucent minerals. Phosgenite is also most commonly found leaving a white streak when specimen is rubbed on a white porcelain streak plate. Phosgenite is usually found showing conchoidal fracture when evaluated under polarized microscopes. The best field indicators of mineral Phosgenite usually include density, color, fluorescence, high luster, variable hardness and crystal habit. Phosgenite is most commonly found associated with other interesting minerals including limonite, galena, cerussite and anglesite. Mineral Phosgenite is known to form from the oxidation of lead bearing minerals such as when galena comes in contact with carbonated and chlorinated water. Phosgenite notably occurs at several locaalties including Namibia, Italy, England, Greece and some areas in USA.



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Monday, June 15th, 2009 at 6:09 am
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The Carbonates and Borates Mineral Class
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