Cenosite from Bancroft, Ontario

Cenosite, Ca 2 (Y, Dy, Er etc.) 2 Si 4 O 12 CO 3 XH 2 O, occurs in a vug in pegmatitic granite, Bancroft mine, Bancroft, Ontario. Cenosite crystals are orthorhombic, space group Pmnb, a=13.05, b=14.33, c=6.77; spec. gravity 3.52; optical constants, d=1.665, beta =1.685, gamma =1.689, biaxial negative. Chemical analyses, indexed powder pattern, and infrared spectrum are given.