砷铜矾的发现与研究

Discovery and Study of Parnauite

砷铜矾（Ｐａｒｎａｕｉｔｅ）在１９７８年首次发现于美国，１９８４年笔者在广西德保矿区也发现了这种矿物。笔者发现的这种矿物有两种形态，即纤维状和薄片状。纤维状砷铜矾的化学成分为（％）：ＣｕＯ５８．６９，Ａｓ２Ｏ５１７．４１，ＳＯ３６．５４，ＦｅＯ０．８６，ＳｉＯ２０．０８，（Ｈ２Ｏ１７．７０），其理想分子式为：Ｃｕ９（ＡｓＯ４）２（ＳＯ４）（ＯＨ）１０·７Ｈ２Ｏ，与美国产出的砷铜矾的化学成分基本一致。而薄片状砷铜矾的化学成分为（％）：ＣｕＯ５６．０９，Ａｓ２Ｏ５１８．３９，Ａｌ２Ｏ３０．２１，ＦｅＯ０．４０，ＳｉＯ２０．５６，ＳＯ３５．２０，ＣＯ２３．８３，Ｈ２Ｏ＋１４．４０，总量为９９．０８，其理想矿物分子式为：Ｃｕ９（ＡｓＯ４）２（ＳＯ４）（ＣＯ３）（ＯＨ）８·６Ｈ２Ｏ，这与美国所产出的砷铜矾有一定的差别。该矿物呈翠绿色至灰绿色，透明，玻璃光泽或珍珠光泽，硬度Ｈ＝２。薄片状砷铜矾的实测比重Ｄｍ＝３．３３，计算比重Ｄｃ＝３．３５，二轴晶负光性，Ｎｐ＝１．７０９，Ｎｍ＝１．７３２，Ｎｇ＝１．７３８，２Ｖ＝５４．６３°。纤维状砷铜矾的Ｘ射线粉晶衍射数据与美国砷铜矾基本一致。薄片状砷铜矾的主要衍射强线为１４．８５?

Parnauite was first discovered in the United States in 1978. In China, it was first found in the Debao ore district of Guangxi in 1984. There are two forms of parnauite in Debao: foliated and fibrous. Chemical composition of the foliated parnauite is given as follows (in percentage): CuO 56.09, As 2O 5 18.39, Al 2O 3 0.21, FeO 0.40, SiO 2 0.56, SO 3 5.20, CO 2 3.83, H 2O + 14.40, totally 99.08, suggesting an ideal chemical formula of Cu 9(AsO 4) 2(SO 4)(CO 3)(OH) 8·6H 2O, which is somewhat different from that of parnauite from the United States; nevertheless, the composition of the fibrous parnauite is similar to that of parnauite from the United States. The foliated parnauite is jade green to greyish in color, and transparent, glassy to pearly in luster. H =2, D m=3.33, D c=3.35, biaxial negative. Refractive indices N p= 1.709, N m=1.732, N g=1.738; 2 V =54.63°. The strongest lines in X ray diffraction pattern of the foliated parnauite are 14.85(100), 10.45(15), 7.20(10), 6.46(12), 4.55(60), 4.03(20), 2.867(17), 2.818(10). Orthorhombic system, space group P 2 122, cell dimensions a =14.92, b =14.28, c =6.02,calculated cell dimensions a =15.052(18), b =14.320(7), c =6.002(6), Z =2.