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The chemical formula of mineral Macphersonite is indicated by Pb4SO4(CO3)2(OH)2 or Lead Sulfate Carbonate Hydroxide. Macphersonite is actually a Carbonate mineral. Mineral Macphersonite was named after Harry Gordon Macpherson, a mineralogists at the Royal Scottish Museum. The mineral was actually named as recently as year 1984. The mineral species was discovered at Leadhills, Lanarkshire, Strathclyde, Scotland. Macphersonite is known to crystallize in the orthorhombic system of crystal formation. In optical mineralogy, this crystal system comprises crystals having three mutually perpendicular axes, of which all are of different lengths. Macphersonite is only used as mineral specimens and it is often found exhibiting nice and fascinating appearance under polarizing light microscopes used in optical mineralogy.

 

This mineral species Macphersonite is actually closely related to the still scarce mineral called leadhillite. Mineral Leadhillite and Macphersonite are dimorphs. Two minerals are said to be dimorphs when they share exactly the same chemistry but with different structures. The word di in Latin means two and morph in Latin means shape. And because the two minerals have different structures, this means that they have different symmetries. In this case, mineral Macphersonite is found crystallizing in the orthorhombic system, while leadhillite is monoclinic in symmetry. There is another interesting mineral that was found having the same chemistry and different structure than the two other mentioned. This mineral is called susannite. Mineral susannite is known to crystallize in the trigonal system. Thus, susannite, leadhillite, and Macphersonite is a complete set of trimorph minerals. Due to the presence of sulfate ions in the chemistry of the three minerals, they could actually be classified as sulfates but then they were classified as carbonates because of the significance of the carbonates ions and also due to its greater number.

 

            Mineral Macphersonite is most commonly found colorless, white, amber or brownish in appearance and it is often found exhibiting interesting images when viewed with the aid of polarizing microscope for mineralogists. Macphersonite is commonly found exhibiting adamantine to resinous luster when viewed in reflected light of petrographic polarizing light microscope used in optical mineralogy. Mineral Macphersonite is most commonly found displaying a perfect cleavage in only one direction and it can be seen more clearly exhibited under polarizing microscopes for mineralogists. Macphersonite also exhibits uneven fracture when evaluated under petrographic polarizing light microscopes. The specific gravity measure of mineral Macphersonite is usually found ranging from 6.5 grams per cubic centimeters to 6.6 grams per cubic centimeters, which is considered very heavy for translucent minerals. The hardness measure of mineral Macphersonite when it is evaluated using the Mohs scale method is usually ranging from 2.5 to 3. Macphersonite is most commonly found leaving a white streak when the specimen is rubbed on a white porcelain streak plate.

 

            Most crystals of mineral Macphersonite are found transparent to translucent in appearance. The crystal habit of the mineral Macphersonite as described in optical mineralogy usually include tabular or pseudohexagonal crystals that are more clearly exhibited when evaluated under geological polarizing microscopes. Macphersonite is usually found showing biaxial negative figure when it is evaluated between crossed nicols of petrographic polarizing microscope. The refractive index of Macphersonite when it viewed more closely under polarized microscopes is usually found ranging from 1.870 to 2.010. Macphersonite also exhibits a very high surface relief when it is evaluated under several adjustments on the aperture diaphragm of the petrographic polarizing light microscopes. The maximum birefringence exhibited by Macphersonite between crossed polars of polarizing microscope used in optical mineralogy is usually found 0.140. Some specimens of mineral Macphersonite are found fluorescent yellow under ultra violet light. There is no specific data found on toxicity and health dangers for mineral Macphersonite. However, the specimens of the mineral should be treated with great care and use of sensible precaution is recommended upon handling them. Mineral Macphersonite is a non-radioactive mineral species.

 

            Macphersonite is most commonly found associated with other interesting minerals including leadhillite, galena, cerussite, anglesite, and linarite. The best field indicators of mineral Macphersonite usually include density, locality, crystal habit, color, fluorescence, and luster. Mineral Macphersonite notably occurs at several localities including Leadhills, Lanarkshire, Strathclyde, Scotland and also the Aregentolle Mine, Saint-Prix, Saone-et-Loire, France. There was also a reported discovery of just one specimen of Macphersonite at Moon Anchor Mine, Maricopa County, Arizona.



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Thursday, November 27th, 2008 at 3:46 am
Category:
The Carbonates and Borates Mineral Class
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