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13
Jan

Click Here For Best Selection Of High Quality Polarizing Microscope

Click Here For Best Selection Of High Quality Polarizing Microscope

The chemical composition of mineral Davyne is indicated by the formula Na4K2Ca2Si6Al6O24(SO4)Cl2. This mineral is commonly found in volcanic ejecta and in leucite-rich lavas. Davyne is also found occurring from its type of locality at Monte Somma, Vesuvius, Italy. Mineral Davyne was named for Sir Humphrey Davy (1778-1829), famous English chemist who discovered the following elements: B, Ba, Ca, K, Mg, Na, and Sr. Davyne is known to crystallize in the hexagonal system of crystal formation. In optical mineralogy, the hexagonal system of crystallization comprises crystals having four axes. Three of which are positioned in a single plane with equal length and are symmetrically spaced. The fourth axis is found to be perpendicular to the other three axes. It is known to have perfect cleavage in one direction and indistinct in the other, all of which can be found more clearly exhibited when viewed with the aid of petrographic polarizing microscope. Davyne is commonly found colorless or white in hand sample. The density measure of mineral Davyne is usually found ranging from 2.42 to 2.53 grams per cubic centimeters with an average of 2.47. Most crystals of mineral Davyne are found transparent in appearance. Davyne is also found with brittle to conchoidal fracture under petrographic polarizing microscope used in optical mineralogy. This is a very brittle fracture producing small, conchoidal fragments. The crystal habit of mineral Davyne as described in the field of optical mineralogy includes hexagonal or six-sided crystal shape in cross-section or habit. Davyne can also be found prismatic in form with crystals shaped like slender prisms similar to tourmaline. The hardness measure of mineral Davyne is usually found 6 when evaluated using the Mohs scale method. Davyne is also found showing vitreous or glassy luster in reflected light of polarizing microscope for mineralogists. Mineral Davyne is also found leaving a white streak when rubbed on white porcelain streak plate. This mineral is also found with uniaxial positive figure and birefringence ranging from 0.0010 to 0.0050 when specimen is evaluated between crossed nicols of polarized microscope. Davyne has barely detectable radioactivity after chemically evaluated.



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Friday, January 13th, 2012 at 4:01 am
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Optical Mineralogy
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