Silver Valley limestone (blue limestone) is one of the most widely distributed gray or gray sedimentary rocks in the crust generated in the sea and lake basin (about 15% of the lithosphere),Water absorption rate 0.75%, bending strength 10.0MPa, gloss around 60, density 2800 kg/m, Silver Valley limestone (blue limestone)belongs to the limestone category, marble composition is also limestone, so blue limestone is also a marble category.