Damaraite, a new lead oxychloride mineral from the Kombat mine, Namibia (South West Africa) A. J. CRIDDLE,l P. KELLER,2 C. J. STANLEY' and J. INNES3 IDepartment of Mineralogy, The Natural History Museum, Cromwell Rd., London SW7 5BD, U.K. 2Institut flir Mineralogie und Kristallchemie, Universitat Stuttgart, 0-700 Stuttgart, Germany 3CSIRO Division of Exploration Geoscience, Private Bag, Wembley, Western Australia 6014 Abstract Damaraite, ideally 3PbO.PbCI2, is a new mineral which occurs with jacobsite, hausmannite, hemato- phanite, native copper, an unnamed Pb-Mo oxychloride, calcite, and baryte, in specimens from the Asis West section of the Kombat mine, Namibia (South West Africa). Damaraite is colourless and transparent with a white streak, and adamantine lustre. It is brittle with an irregular to subconchoi- dal fracture and a cleavage on (010). The mineral has a low reflectance, a weak bireflectance, barely discernible reflectance pleochroism, from grey to slightly bluish grey in some sections, and is weakly anisotropic. Reflectance data in air and in oil are tabulated. Colour values relative to the CIE illuminant C for the most strongly bireflectant grain are, for R I and R2 respectively: Y%15.9, 16.9; Ad475, 472; Pe %5.3, 8.9 It has a VHN50 of 148 (range 145-154) with a calculated Mohs hardness of 3. X-ray powder diffraction studies give the following parameters refined from the powder data: orthorhombic; space group Pma2, Pmam or P2]am; a 15.104(1), b 6.891(1), c 5.806 (1)A; V is 604.3 (4)A3 and Z=3. Deale7.84 g/cm3. The strongest six lines of the powder pattern are [d in A (I) (hkl)]: 2.902 (10) (121,002); 2.766 (10) (510,221); 2.877 (9) (411); 3.164 (6) (401); 3.135 (6) (220); 1.747 (b) (313,721,531). The name is for the Damara sequence which hosts the Kombat deposit. KEYWORDS: damaraite, new mineral, lead oxychloride, Kombat mine, Namibia. Introduction and general geology minerals (reminiscent of some of the assemblages at Uingban, Sweden, and Franklin, New Jersey) DAMARAITE, a new lead oxychloride, was disco- and the new species johninnesite (Dunn et al., vered in specimens collected from hematopha- 1986), kombatite (Rouse et al., 1986), ribbeite nite-bearing assemblages in a manganese ore lens (Peacor et al., 1987), holdawayite (Peacor et al., on the 1208 metre sill elevation of the W90 1988) and asisite (Rouse et al., 1988). (south-east) stope on the 12 level of the Asis West The lenses of manganese ore (consisting predo- section of the Kombat Mine. The mine is sited minantly of hausmannite), are fine to coarse- on the northern flank of the Otavi Valley, 37 km grained: their strongly deformed mineral and tex- east of Otavi and 49 km south of Tsumeb, in turallayering mimics the banding of the protore northern South West Africa/Namibia (lat. 19°45'S which, it is believed, represents a syngenetic long. 17°45'E) and is a medium-rank producer accumulation of bedded manganese oxides, hyd- of high-grade Cu-Pb-Ag ores formed by hydro- rated oxides and siliceous exhalites, originally thermal and metasomatic replacement and frac- deposited fumarolically at a sub-aqueous inter- ture-fill of dolostones of the Upper Proterozoic face between environments of shallow-water car- Hiittenberg Formation. The geology of the bonate and euxinic sedimentation. deposits has been described by Innes and Chaplin Many of the rare minerals were found in late- (1986). stage hydrothermal ptygma-like veins, which are Since 1974, a series of small lenses of manga- transgressive to the primary layering of the haus- nese and iron ores associated with Cu-Pb-Ag sul- mannite ores, and are commonly zoned. phide ores has yielded an extensive suite of rare During the week ending 29/6/84, the mill super- Mineralogical Magazine, December 1990, Vol. 54, pp. 593-598 @ Copyright the Mineralogical Society 594 A. J. CRIDDLE ET AL. TABLE 1. Reflectance data for damaraite ------------- -------------.-.-. ....-------- 1 " 2 3 4 imR1 irnRZ imR1 irnRZ imR1 irnRZ imR1 imRZ '1 '2 '1 '2 '1 '2 '1 ~--_.-~._-------'2 400 19.1 20.8 18.9 20.1 19.2 19.9 19.0 19.8 6.31 7.55 6.22 7.27 6.25 6.99 6.03 6.86 420 18.6 23.1 16.5 22.55 18.4 19.0 18.2 18.9 5.97 9.23 5.87 8.97 5.88 6.30 5.58 6.15 440 17.9 21.1 17.9 21.1 17.8 18.3 17.6 18.1 5.58 7.78 5.54 7.76 5.63 5.90 5.30 5.79 460 17.35 19.4 17.3 19.25 17.4 17.7 17.15 17.5 5.26 6.58 5.20 6.51 5.38 5.58 5.01 5.41 470 1L.!2 l!!,2> 1L1 1!L.l2 J.L.l lU .!Q.,2 J.L.l 2.J.l 6.27 hQI ~~5.43 4.89 UI 480 16.9 18.5 16.9 18.35 17.0 17.3 16.7 17.0 5.00 6.02 4.94 5.92 5.16 5.30 4.77 5.14 500 16.55 17.9 16.55 17.75 16.7 16.9 16.4 16.6 4.80 5.64 4.75 5.56 4.97 5.08 4.58 4.92 520 16.25 17.4 16.25 17.3 16.4 16.55 16.1 16.25 4.65 5.37 4.60 5.31 4.84 4.91 4.42 4.75 540 16.0 17.05 16.0 16.9 16.1 16.25 15.9 16.0 4.51 5.15 4.45 5.08 4.70 4.76 4.29 4.61 546 lLZ 1l.,Q lLZ 1Q.& 1Q..,Q .!2.d l2.J! lLZ ~5.09 ~5.03 4.67 4.73 ~4.59 560 15.8 16.7 15.8 16.65 15.9 16.0 15.7 15.8 4.40 4.97 4.35 4.93 4.59 4.63 4.19 4.51 580 15.6 16.5 15.6 16.4 15.75 15.8 15.55 15.6 4.33 4.85 4.28 4.80 4.51 4.54 4.11 4.44 589 l2..,22 1Qd l2..,22 J.Q.,d !2,2 J2.,Q 4.28 4.79 ~4.74 4.48 4.09 4.40 1U: l2.J! "-dQ 600 15.5 16.3 15.5 16.25 15.6 15.7 15.45 15.5 4.25 4.75 4.22 4.71 4.44 4.46 4.08 4.39 620 15.4 16.15 15.4 16.1 15.5 15.6 15.4 15.4 4.20 4.66 4.18 4.63 4.41 4.41 4.03 4.34 640 15.25 16.0 15.3 15.95 15.4 15.5 15.3 15.35 4.17 4.60 4.14 4.57 4.36 4.35 3.98 4.30 650 .!2.ill 1Q..,Q l.U lLZ .!.2..d .!2.ill l.U U2. 4.57 h1l ~4.34 ~3.96 li'"'- "-E 660 15.15 15.9 15.2 15.85 15.35 15.4 15.25 15.3 4.13 4.54 4.11 4.53 4.32 4.30 3.94 4.26 680 15.1 15.75 15.15 15.75 15.25 15.3 15.15 15.2 4.09 4.50 4.07 4.47 4.28 4.27 3.89 4.21 700 15.0 15.65 15.1 15.65 15.2 15.15 15.1 15.1 4.07 4.45 4.03 4.43 4.25 4.22 3.88 4.20 ~------._.._~-~---~-_.__.._._----- Colour values reLative to CIE I Lluninant C .300 .293 .300 .294 .300 .299 .301 .299 .291 .278 .291 .279 .293 .290 .291 .291 .304 .294 .304 .294 .305 .303 .305 .303 .293 .272 .293 .272 .296 .293 .293 .292 Y% 15.9 16.9 15.9 16.8 16.0 16.15 15.8 15.9 4.47 5.09 4.42 5.04 4.65 4.70 4.26 4.59 475 472 474 471 475 475 474 473 474 470 473 469 475 474 474 473 pe% 5.3 8.9 5.2 8.8 4.8 5.6 4.8 5.5 9.8 17.1 9.7 17.0 8.6 10.1 9.6 9.9 -------~~---~ intendent at the Kombat Mine noted a dense jacobsite- hausmannite- baryte-calcite- native- reddish-brown mineral in the sulphide concen- copper -vesuvianite-hematophanite; jacobsite- trate during the froth flotation process: when this he ma tophanite-baryte-hemati te-na tive-copper- was separated it was identified as hematophanite. asisite~molybdophyllite-chlorite and hematopha- A subsequent search underground resulted in the nite-andradite-vesuvianite-baryte) were recov- discovery of hematophanite in situ as a constituent ered both from the layered hausmannite ores and of banded hausmannite-baryte-jacobsite-hema- from a meshwork of ptygma-like veins of baryte- tite ores in the W90 stope. Here, the hematopha- calcite-jacobsite-hematite. The type specimen of nite formed layers (up to 17mm in thickness) of damaraite (mine sample number MINA 02 0884) densely packed aggregates of micaceous flakes is from the late-stage vein paragenesis. The W90 (themselves up to 4mm wide), associated with stope is also the type locality for the recently des- native copper.