Turquoise is an opaque, green-to-blue mineral that is a hydrous phosphate of aluminum and copper. Since it is a hydrous phosphate, if you dip Turquoise in water or any similar liquid, it will absorb the liquid. On the Mohs scale of mineral hardness, turquoise ranks between five and six, just below quartz stone. It is a porous mineral and its occurrence is rare in nature. Most of the gem-grade turquoise is either found in host rocks, or in nodule deposits. In these deposits, it exists either as shallow crusts or veins.