摘要
墨绿砷铜石和羟砷铜石为砷酸盐矿物,于1984年发现于广西省德保矽卡岩型铜—锡矿床氧化带中,在我国尚属首次发现。笔者对其进行了物理性质、化学成分的研究,并进行了X射线粉晶分析、红外光谱分析以及差热分析,其结果是化学成分与X光粉晶数据与国外已知数据基本一致,补充了这两种矿物的红外光谱数据和差热分析数据,从而提高了这两种矿物的研究程度。通过研究,发现这两种矿物化学成分相近,但结构晶系相异,二者常密切共生。文章最后还探讨了这两种矿物的成因。
Cornwallite and cornubite were found in oxidized zone of the Debao skarn type Cu-Sn ore deposit in Guangxi. The former is jade green and bluish green in color and radial-fibrous, platy and botryoidal in form. The wet chemical analysis shows its composition to be CuO 60.96, As_2O_5 30.53, Al_2O_3 0.13, SiO_2 0.68, P_2O_5 0.50, FeO 0.15, H_2O^+ 6.98, totally 99.93 (in percentage), with the ideal chemical formula being [Cu_5(AsO_4)_2(OH)_4·H_2O]·The X-ray powder data agree with JCPDS 12-287, and the strong diffraction lines are 4.77(210)(3), 4.56(001)(7), 3.52(111)(10), 3.21(401)(8), 3.12(311)(5), 3.02(311)(5), 2.74(411)(5), 2.49(511)(4), 2.43(601)(6), 2.30(611)(6), 1.888(3), 1.773(4), 1.651(7), 1.532(3). Calculated cell dimensions a=17.547, b=5.914. c=4.666, β=91.6°, Z=2; monocliuic, space group P2_1/a. H=4, D(mean)=4.43. Refractive indices: Ng=1.846, Nm=1.843, Np=1.833(±0.002). Biaxial negative, 2V=60°-70°The cornubite is green or greyish green in color aud botryoidal in form. The electron microprobe analyses of four grains are CuO 62.29％, As_2O_5 31.54％, FeO 0.20％ and SiO_2 0.13％ (H_2O^+ undetermined), suggesting an ideal chemical formula of [Cu_5(AsO_4)_2(OH)_4]. The X-ray powder data are basically consistent with JCPDS 12-228. The strong diffraction lines are 5.355(20), 4.711(100), 4.585(30), 3.587(30), 3.492(70), 3.101(30), 2.683(80), 2.557(40), 2.483(40), 2.300(50), 1.746(30), 1.571(30), 1.519(30), 1.374(20). H=4. D(mean)=4.51, Biaxial negative, 2V=30°-40° (eye estimation). Refractive indices n=1.75-1.85±(n=1.798 as calculated by Graston formula).
出处
《岩石矿物学杂志》
CAS
CSCD
1989年第1期71-78,共8页
Acta Petrologica et Mineralogica
