新疆罗布泊地区水硝碱镁矾和钠硝矾的矿物学研究

MINERALOGICAL STUDIES OF HUMBERSTONITE AND DARAPSKITE IN LUOBUBO REGION; CHINA

本文报道了我国新发现的两个硝酸盐-硫酸盐复盐矿物——水硝碱镁矾和钠硝矾。水硝碱镁矾呈假四方双锥状,属三方晶系,解理{0001}完全,一轴负晶,折光率为ω=1.474,ε=1.436:晶胞参数α=1.0894nm,c=2.4396nm,粉晶图的强衍射线为:2.813(100),8.096(19)1.991(18),3.391(10),2.199(8),8.751(8)。钠硝矾为板状,板柱状,解理{010}完全,{100}不完全。聚片双晶平行(100),二轴负晶,折光率为:α=1.487,β=1.481,γ=1.391;-2V=28°。矿物属单斜晶系,晶胞参数为:α=1.0565nm,b=0.6922nm,c=0.5194nm。粉晶图的强衍射线为:10.3(100),3.46(35),2.594(30),2.871(30),2.856(30),4.13(20)。文中还列出了两矿物的差热和红外吸收光谱等资料。

Two sulfate-nitrate minerals——humberstonite and darapskite, found in Luobubo, Xinjiang, China, are discussed in this paper. Thelr mineralogical data are presented as follows: humberstonite, pseudotetragonal dipyramid, observed single forms: a{0001}, r{1011}, d{0112}, and ε=1.436, ω=1.474. The mineral is of trigonal system, with the unit cell parameters: α=1.0894nm, c=2.4396nm. The strongest lines in the X-ray diffraction pattern are: 2.813(100), 8.096(19) 1.991(18), 3.391(10), 2.199(8), and 8.751(8). Che mical composition (wt.%) is. SO_3 41.47, N_2O_5 9.80, Na_2O 21.01, MgO 6.01, K_2O 12.84, H_2O 9.40, total 100.53. Evidently, the content of water is less than nitrogen oxide and slightly different from Ericksen's. But the formula is in agreement with K_3Na_7Mg_2(SO_4)_6·(NO_3)_2·6H_2O given by G.E.Ericksen. Darapskite, prismatic habit, observed single forms: {100}, {010}, {001},{110}, has a perfect cleavage(010) and an uneven fracture parallel to (100), as well as polysynthetic twinning parallel to(100). Its optical data: α=1.487, β=1.481, γ=1.391, Ng∧c=12°32′-2V=28°. The mineral is of monoclinic system, with α=1.0565nm, b=0.6922nm, c= 0.5194nm, β=102°54′. The strongest lines in the X-ray diffraction pattern are:10.3(100), 3, 46(35), 2.594(30), 2.871(30), 2.856(30), and 4.13(20).