青海、西藏的水钙芒硝

HYDROGLAUBERITE FROM QINGHAI AND XIZANG

水钙芒硝(Hydroglauberite)是1969年由苏联斯柳萨列娃发现定名的新矿物。由于颗粒非常细小,晶形不佳,她仅列出光学性质、X射线粉晶分析和化学分析等资料。 1964年在我国青海某盐湖湖底淤泥中发现了细针状水钙芒硝。当时由于样品很少,颗粒太小,仅作了光性测定及X射线粉晶分析。近年来我们在青海及西藏一些盐湖中又发现了水钙芒硝,而且量较多,晶形良好。 我们通过进一步研究,证明斯柳萨列娃所报道的新矿物实际上含有大量的无水芒硝等杂质,从而造成某些数据的较大误差。

Hydroglauberite, a new mineral reported by M. N. Slyusareva in 1969, was also found in some salt lakes in Qinghai and Xizang (Tibet), China.Our work has confirmed that the mineral reported by M. N. Slyusareva is in fact a mixture of hydroglauberite and thenardite. There is a striking discrepancy between the specific gravity, index of refraction and chemical composition measured by M. N. Slyusareva and those measured in terms of the Gladstone-Dale relationship.Detailed studies have been made on the mineral discovered in China and some new data have been obtained.The lattice constants of hydroglauberite are: a_0=6.49, b_0=18.78, c_0=6.96 and α=β=γ=90°. The strongest lines are: 2.92(10), 2.75(8), 3.45(7), 5.50(6) and 3.06(6).The chemical formula of hydroglauberite is Na_2SO_4.CaSO_4·2H_2O; the optical constants: Ng=1.5015, Nm=1.4990, Np=1.4886, 2V=44°; the specific gravity: 2.42.