Mazzite,a new mineral,the natural counterpart of the synthetic zeolite Ω

Mont Semiol (also called Mont Semiouse), Montbrison, Loire, France, is the only place where the zeolite offrettite is known to occur. Now, a new mineral, Mazzite, has been found in the same locality. It occurs in the form of tiny needles, and its properties closely match those of the synthetic “molecular sieve” Ω. The chemical formula is Na_0.03K_1.91Ca_1.35Mg_1.99[Al_9.77Si_26.54O₇₂]·28.03 H₂O. Lattice dimensions are a=18.392 Å, c=7.646 Å, with P 6₃/mmc as most probable space group; D_calc.=2.108. Offrettite and mazzite occur in association with phillipsite, chabazite, calcite and siderite. The mineral has been so named in honour of Prof. Fiorenzo Mazzi.