墨绿砷铜石与假孔雀石的中间端员组份矿物──砷假孔雀石的发现

The Discovery of Arsenopseudomalachitean Intermediate Member of Cornwallite Pseudomalachite Isomorphic Series

关键词:  砷假孔雀石  砷酸盐矿物  矿物学特征  广西

Key words:  Arsenopseudomalachite  Hydrated Arsenate Mineral  Mineralogic Characteristies  Guangxi

摘要:

砷假孔雀石是墨绿砷铜石与假孔雀石的中间端员组份矿物,首先发现干中国广西德保矿区硫化铜矿床铁帽带,该物的发现使不同族的墨绿砷铜石和假孔雀石联成一类质同象系列。该物的化学成份为CuO 63.32%、As₂O₅ 22.20%、P₂O₅ 8.93%、SO₃ 0.56%、H₂O 5.53%。晶体呈翠绿色粒状,斜方桂状,透明,硬度H=4,实测比重4.59,χ射线衍射特征强线为4.83(59)4.59(91)3.96(45)3.21(95)3.11(100)3.02(93)2.89(60)2.49(61)2.47(97)2.415(96)1.878(44)1.793(44)1.764(45),晶胞参数a₀=16.95(5)Å、b₀=5.84(1)Å、C₀=4.60(2)Å、β=93°.00(7),Z=2。单斜晶系,空间阵P2_1/a。

Abstract:

Arsenopseudomalachlie was found with other secondary copper arsenate minerals in shuangwall hill, Debao mine, Guangxi China. Its chemical composition was CuO 63.32%, As₂O₅22.20%, P₂O₅ 8.93%, SO₃ 0.56% (by EPMA), H₂O 5.53% (by thermal gravimetric analysis),giving a chemical formular of Cu_5.00[(A₅O₄)_1.21.(PO₄)_0.79]_2.00 (SO₄)_0.04 (OH)_3.85. Its crystals were short prism, emeral green in color, Transparent, D(mean)=4.59, D(calc)=4.61, H=4. Average refractive index was 1.885, the stronger lines in X-ray diffraction pattern were:5.51 (37) (110), 4.83(59) (210), 4.59 (91) (001), 3.96 (45) (201), 3.54(88) (111), 3.33 (50) (211),3.21 (95) (401), 3.11 (100) (311), 3.02(93) (401), 2.98(55) (311), 2.89(60) (120), 2.74(64) (220), 2.59 (50) (320), 2.53 (54) (511), 2.49 (61) (601), 2.47 (97) (021), 2.415 (96) (700),2.346 (58) (221), 2.283 (58) (321), 2.223 (44) (321), 2.169 (46) (611), 2.117 (43) (800),1.878(44) (801), 1.794 (44) (031), 1.770 (41) (430), 1.764 (45) (231), 1.756 (43) (721),1.689 (42) (530), 1.637 (45) (431), 1.631 (41) (422), 1.606 (39) (802), 1.581 (38) (920),1.579 (43) (821), 1.549 (38) (812), 1.517 (38) (730), 1.453 (37) (232), 1.441 (40) (1111),1.440(39) (240), 1.433 (37) (830), 1.422 (37) (332), 1.393 (36) (041), 1.386 (34) (141),1.346(35) (341), 1.337(38) (632), 1.331 (35) (441), calculated unit cell parameters:
a₀=16.95 (5)Å, b₀=5.84 (1)Å, c₀=4.60 (2)Å, β=93°.00 (7), and Z=2, monoclinic system,space group:P2_1/a.
The infrared spectra showed absorption bands at 3427, 3350, 1810 (cm^-1) of (OH)^-; at 1082, 1027, 992, 611, 525 (cm^-1) of (PO₄)^3-; at 831, 800, 770, 447 (cm^-1) of (A₅O₄)^3-,Thermal analysis showed endothermic peak at 560℃ lost 5.53% of weight.