The chemical formula of mineral Phillipsite-Ca is indicated by CaK0.6Na0.4Si5.2Al2.8O16.6(H2O). Phillipsite-Ca is a common zeolite in volcanic rocks, ore veins, diagenetically altered rhyolitic tuffs, saline lake deposits, and ocean floor sediments. It usually shows solid solution toward harmotome. Phillipsite-Ca was named after William Phillips 91775-1829), an English mineralogists and a known founder of the Geological Society of London. The Ca-dominant member of the Phillipsite Series. Mineral Phillipsite-Ca is known to crystallize in the monoclinic system of crystal formation. In optical mineralogy, the monoclinic system of crystal formation comprises crystals having three axes of unequal lengths. Two of which are usually found in a position that is oblique or not perpendicular to one another. However, both of which are commonly found perpendicular to the third axis. Phillipsite-Ca is usually found showing distinct cleavage in one direction and indistinct cleavage in the other which can be found more clearly exhibited when specimens are viewed closely with the aid of petrographic polarizing light microscope used in optical mineralogy. Phillipsite-Ca is usually found white, reddish white, light yellow or pink in color that could actually appear more splendid when viewed with the aid of polarized light microscopes for mineralogists. The specific gravity measure of mineral Phillipsite-Ca is usually found 2.2 grams per cubic centimeters. Most Philipsite-Ca crystals are found translucent to opaque in appearance. The fracture that is commonly exhibited by the mineral is usually uneven. In the field of optical mineralogy, this appears as flat surfaces fractured in an uneven pattern. Phillipsite-Ca is usually found forming prismatic crystals shaped like slender prisms. It also forms pseudo-tetragonal crystals that show a tetragonal shape when viewed with the aid of polarized microscopes used in optical mineralogy. Twinning is also common in Phillipsite-Ca crystals. The hardness measure of the mineral when it is evaluated using the Mohs scale method is usually found 4.5. It also exhibits vitreous luster when viewed in reflected light of petrographic polarizing light microscopes. Phillipsite-Ca is most commonly found leaving a white streak when rubbed on a white porcelain streak plate. Phillipsite-Ca is usually found showing biaxial figure when evaluated between crossed nicols of polarized microscopes. It has 0.0030 to 0.0090 birefringence. Phillipsite-Ca is a slightly radioactive mineral.
