Mazzite-Na, a new zeolite from Boron, California: Its description and crystal structure

摘要

Mazzite-Na, Na₈Al₈Si₂₈O₇₂·30H₂O, is a new zeolite mineral species occurring in basalt at the bottom of the open pit of the U.S. Borax mine at Boron, California. It crystallizes as white, very thin, flexible fibers up to 2 mm in length, and commonly fills small cavities as satiny mats. The luster is vitreous, and the streak is white. The fineness of the fibers precludes the determination of the hardness and the observation of any cleavage. The observed and calculated densities are 2.16 and 2.18 g/cm3, respectively. The mineral is uniaxial positive with n = 1.472(3) and n = 1.471(3). Electron-microprobe analyses yielded (in wt%) SiO₂ 57.65, Al₂O₃ 14.35, Fe₂O₃ 0.65, MgO 0.22, CaO 0.18, BaO 0.14, Na₂O 8.07, K₂O 0.03, and H₂O 18.70 (TG analysis), which gives the empirical cell contents (Na_7.52K_0.02Mg_0.16Ca_0.09Ba_0.03)[Fe_0.24Al_8.13Si_27.71O₇₂]· 29.98H₂O. Mazzite-Na is hexagonal, P6₃/mmc, a = 18.2343(7), c = 7.6371(2) Å, Z = 1. The strongest seven measured X-ray lines [d in Å(I)(hkl)] are: 9.08(100)(110), 6.86(70)(101), 5.95(70)(210), 4.681(40)(211), 3.787(80)(002), 3.511(40)(112), and 3.150(70)(500).