The chemical composition of mineral Caysichite-(Y) is indicated by the formula Y2(Ca,Gd)2Si4O10(CO3)3(H2O,O,OH)•3H20. Caysichite-(Y) commonly occurs in granite pegmatite lining cavities. Caysichite-(Y) is most commonly found at Evans-Lou feldspar mine, Portland West Township, Quebec, Canada. Caysichite-(Y) was named for the composition (Ca, Y, Si, CO3). Caysichite-(Y) is known to crystallize in the orthorhombic system of crystal formation. In optical mineralogy, this orthorhombic crystal system comprises crystals having three mutually perpendicular axes, of which all are of different lengths. Caysichite-(Y) has an indistinct cleavage found when evaluated using petrographic polarizing microscopes. Mineral Caysichite-(Y) is also commonly found colorless, green, greenish yellow, white, or light yellow in hand sample. The density measure of mineral Caysichite-(Y) is usually found 3.03 grams per cubic centimeters. Caysichite-(Y) is usually found with transparent crystals. The crystal habit of mineral Caysichite-(Y) as described in the field of optical mineralogy usuallyy includes pulverulent crystals forming a loose, poorly-coherent powdery mass. Sometimes it can be also found reniform or “Kidney like” in shape similar to hematite. It can be also found stalactitic or shaped like pendant columns as stalactites or stalagmites similar to calcite. The hardness measure of mineral Caysichite-(Y) is usually found 4.5 when evaluated using Mohs scale method. Caysichite-(Y) is exhibiting Cathodoluminescence. Caysichite-(Y) is also exhibiting vitreous to glassy luster in reflected light of polarized microscopes used in the field of optical mineralogy. It is also commonly found leaving a white streak when rubbed on white porcelain streak plate. Caysichite-(Y) is commonly showing biaxial negative figure when evaluated between crossed nicols of polarizing microscopes. Caysichite-(Y) is also showing 0.0350 to 0.0370 birefringence. Caysichite-(Y) is also found with mild radioactivity.