ZOISITE CHARACTERISTICS Origin of the name: From the Austrian naturalist and mineralogist Sigmund Zois. Chemical Composition: Calcium aluminum silicate, Ca2Al3(O(OH)SiO4)SiO7). Hardness: Between 6 and 6.5. Crystal system: Orthorhombic Deposits: Austria, United States, Kenya, Switzerland, Tanzania. Color(s): Green, Black, Red, Purple. History and Legends: Lithotherapy Properties: Physical Properties: Signs of the zodiac: Chinese signs: Chakra: