Cotunnite, Cumengeite, Diaboleite and Other Lead and Copper Secondary

Home , Anglesite, Atacamite, Boleite, Caledonite, Chloroxiphite, Cotunnite

Cotunnite PbCl2 Atacamite Cu2(OH)3Cl Cotunnite, cumengeite, diaboleite and other lead and Cotunnite is a relatively common mineral in one of Atacamite appears as small crystalline crusts of copper secondary minerals in the La Reixidora mine the old galleries of this mine, appearing inside vugs in green color, associated with anglesite, cerussite, and cavernous quartz, associated with oxides of iron and linarite, in the schistosity planes of the mica schists. - Monte Bedures, Meredo, Vegadeo, Asturias, Spain - manganese and occasionally with anglesite, cerussite It is easy to distinguish in this locality, since it is the and cumengeite. only green copper It is found forming mineral that appears ( ) Miguel Calvo and Joan Viñals compact crusts in this association. of white color, The morphology of waxy aspect, individual crystals, and coloform extremely small, can Introduction the Los Cabos series, of Middle Cambrian - Lower texture, sometimes only be observed by On the slopes of Monte Bedures (or Monte Vidures), Ordovician age. Currently the galena appears only relatively thick, scanning electron a hill located in the parrish of Meredo, municipality as disseminations or small grained masses, and the which can cover microscopy. of Vegadeo, Asturias, are the remains of a series of chalcopyrite as grains of millimetric size. However, surfaces of several mine workings, some of them very old. These mines the relative scarcity of carbonate and the presence square centimeters. Diaboleite were probably worked in Roman times, for both lead of chloride in the medium have lead, despite the The coloform Pb2CuCl2(OH)4 and iron ores, and possibly also copper. Paillette and very simple primary mineralization, to an “exotic” texture is Diaboleite appears Bezard (1849) located two types of smelting slag in paragenesis of secondary minerals, especially copper maintained even forming small this area, one ferruginous and another plumbiferous, and lead chlorides with no known equivalent until when the mineral dendritic growths, of more precisely in El Escobal, next to Lormes creek. now in Spanish geology. This paragenesis is found is examined by millimetric length, In the decade of the 1830s the Union Asturiana in fissures in grey or light brown mica schists, and scanning electron very thin, probably due company tried to exploit it again, although with is especially interesting since these are secondary microscopy. to the narrowness of th few results. In the first half of the 20 century the minerals but were formed before the completion of Even using the veins in which they Empresa Fábrica de Mieres extracted a siderite iron mine workings, contrary to what happens in other this technique, have formed. It has an ore, more or less transformed into goethite, which in locations. In addition, other secondary minerals microcrystals can intense blue colour, some parts were also rich in manganese. appear in another distinct association, within be observed only and in the examined One of these old workings, in which iron ores cavernous quartz, associated with iron oxides. very occasionally, Cotunnite forming a crust on iron and manganese oxides. specimens it is not La Reixidora mine, Vegadeo, Asturias. FOV 5.5 cm. are scarce, and that was probably exploited for Given that the primary mineral exploited was always with very directly associated M. Calvo coll. Photo J. Callén. argentiferous galena, is located on the NE hillside, in supposedly argentiferous galena, it is noteworthy rounded faces and with any other mineral. the area near the top of the mountain known locally that no secondary silver-bearing minerals have been edges. Cotunnite is a rare mineral, which until now had Considering the deposits of this mineral on a global by the name La Reixidora, or Reixidoira. The primary found so far, such as chlorargyrite or boleite. All the been reported in Spain only in a few mines in the area scale, it seems that diaboleite is relatively common as a mineralization consists mainly of galena, with some minerals described here have been identified by SEM- of Cabo de Palos, in Cartagena, Murcia, as a product result of the alteration of old slags, but nevertheless is a chalcopyrite, and can be found in mica schists of EDS and by X-ray diffraction. of alteration of galena in ferruginous veins (Guardiola, rare mineral in natural deposits. This is the first deposit 1927). However, it is likely that it has gone unnoticed in in which this mineral is reported in Spain, and one of other locations given its inconspicuous appearance. the few existing natural deposits in Europe.

Diaboleite. Dendritic aggregates in a fracture in slate. Cotunnite. Coloform aggregates and corroded microcrystals. SEM photo J. Viñals. Atacamite microcrystals. SEM photo J. Viñals. FOV 4 mm. M. Calvo coll. Photo J. Callén.

26 MINERAL up, Volume 5 n.1, June 18’ MINERAL up, Volume 5 n.1, June 18’ 27 Cotunnite PbCl2 Atacamite Cu2(OH)3Cl Cotunnite, cumengeite, diaboleite and other lead and Cotunnite is a relatively common mineral in one of Atacamite appears as small crystalline crusts of copper secondary minerals in the La Reixidora mine the old galleries of this mine, appearing inside vugs in green color, associated with anglesite, cerussite, and cavernous quartz, associated with oxides of iron and linarite, in the schistosity planes of the mica schists. - Monte Bedures, Meredo, Vegadeo, Asturias, Spain - manganese and occasionally with anglesite, cerussite It is easy to distinguish in this locality, since it is the and cumengeite. only green copper It is found forming mineral that appears ( ) Miguel Calvo and Joan Viñals compact crusts in this association. of white color, The morphology of waxy aspect, individual crystals, and coloform extremely small, can Introduction the Los Cabos series, of Middle Cambrian - Lower texture, sometimes only be observed by On the slopes of Monte Bedures (or Monte Vidures), Ordovician age. Currently the galena appears only relatively thick, scanning electron a hill located in the parrish of Meredo, municipality as disseminations or small grained masses, and the which can cover microscopy. of Vegadeo, Asturias, are the remains of a series of chalcopyrite as grains of millimetric size. However, surfaces of several mine workings, some of them very old. These mines the relative scarcity of carbonate and the presence square centimeters. Diaboleite were probably worked in Roman times, for both lead of chloride in the medium have lead, despite the The coloform Pb2CuCl2(OH)4 and iron ores, and possibly also copper. Paillette and very simple primary mineralization, to an “exotic” texture is Diaboleite appears Bezard (1849) located two types of smelting slag in paragenesis of secondary minerals, especially copper maintained even forming small this area, one ferruginous and another plumbiferous, and lead chlorides with no known equivalent until when the mineral dendritic growths, of more precisely in El Escobal, next to Lormes creek. now in Spanish geology. This paragenesis is found is examined by millimetric length, In the decade of the 1830s the Union Asturiana in fissures in grey or light brown mica schists, and scanning electron very thin, probably due company tried to exploit it again, although with is especially interesting since these are secondary microscopy. to the narrowness of th few results. In the first half of the 20 century the minerals but were formed before the completion of Even using the veins in which they Empresa Fábrica de Mieres extracted a siderite iron mine workings, contrary to what happens in other this technique, have formed. It has an ore, more or less transformed into goethite, which in locations. In addition, other secondary minerals microcrystals can intense blue colour, some parts were also rich in manganese. appear in another distinct association, within be observed only and in the examined One of these old workings, in which iron ores cavernous quartz, associated with iron oxides. very occasionally, Cotunnite forming a crust on iron and manganese oxides. specimens it is not La Reixidora mine, Vegadeo, Asturias. FOV 5.5 cm. are scarce, and that was probably exploited for Given that the primary mineral exploited was always with very directly associated M. Calvo coll. Photo J. Callén. argentiferous galena, is located on the NE hillside, in supposedly argentiferous galena, it is noteworthy rounded faces and with any other mineral. the area near the top of the mountain known locally that no secondary silver-bearing minerals have been edges. Cotunnite is a rare mineral, which until now had Considering the deposits of this mineral on a global by the name La Reixidora, or Reixidoira. The primary found so far, such as chlorargyrite or boleite. All the been reported in Spain only in a few mines in the area scale, it seems that diaboleite is relatively common as a mineralization consists mainly of galena, with some minerals described here have been identified by SEM- of Cabo de Palos, in Cartagena, Murcia, as a product result of the alteration of old slags, but nevertheless is a chalcopyrite, and can be found in mica schists of EDS and by X-ray diffraction. of alteration of galena in ferruginous veins (Guardiola, rare mineral in natural deposits. This is the first deposit 1927). However, it is likely that it has gone unnoticed in in which this mineral is reported in Spain, and one of other locations given its inconspicuous appearance. the few existing natural deposits in Europe.

26 MINERAL up, Volume 5 n.1, June 18’ MINERAL up, Volume 5 n.1, June 18’ 27 Cumengeite Pb21Cu20Cl42(OH)40·6H2O They are associated with earthy iron oxides in Cumengeite has been found as light blue scoriaceous quartz cavities. In some cases, cerussite microcrystals, tetragonal bipyramidal, perfectly crystals have disappeared, leaving a spongy mass of euhedral, with {011} as the main form, modified iron oxides with the holes where these crystals were. by {001} and {110} faces, being proportionally It is also found as somewhat shiny whitish crusts larger the larger the crystals are. This is the first upholstering the surfaces of joints in the slates. deposit from which this mineral is reported in Spain.

Cumengeite is found in two types of associations: Phosgenite Pb2CO3Cl2 either as microcrystals associated with anglesite and Phosgenite appears in schistosity planes of the cerussite in schistose fracture planes of the slates, mica schists as whitish lamellar scabs formed by or associated with cotunnite in vugs in ferruginous morphologically quite complex microcrystals, of an quartz. In this second case the crystals are yet still individual size of less than 100 microns, oriented in smaller. Cotunnite and cumengeite are only formed at parallel. It is associated with cerussite (Calvo, 2012). higher concentrations of Cl- in the medium than the It is practically impossible to distinguish from Phosgenite Microcrystals in parallel grown. Linarite. Cristals with irregular ends. other chlorides of Pb and Cu. The joint presence of cerussite and anglesite without individually analysing SEM photo J. Viñals. SEM photo J. Viñals. both minerals indicates that the pH of the medium was the specimens. between 4 and 5, with a particularly high Cl- content Caledonite Pb5Cu2(SO4)3(CO3)(OH)6 (Humpreys et al., 1980). Anglesite PbSO4 In this mine, anglesite appears as crusts of colorless or In this mine, caledonite appears as aggregates of acicular or bacillary crystals, up to 1 millimetre in Aragonite CaCO3 white microcrystals, sometimes grouped in parallel, Occasionally, aragonite has been found in the La covering some schistosity planes of the slates that length, very well defined, elongated according to [001], Caledonite (group of microcrystals on Reixidora mine as divergent aggregates of colorless contain galena. It is very often associated with formed by the combination of the pinacoids {010} the left) and linarite (on the right). and {100} with the dome {101}, with modifications of microcrystals, with the appearance of sharp wedges, atacamite (Calvo, 2014). The color difference between the species small prism faces, probably {120}. forming spheres and hemispheres on the slates. is evident. FOV 4 mm.

Linarite PbCu(SO4)(OH)2 M. Calvo coll. Photo J. Callén.

Cerussite PbCO3 The linarite appears as crusts of microcrystals of In the La Reixidora mine, cerussite is found as tabular prismatic development and of the intense blue color crystals that are quite thin, colourless and transparent, typical of this mineral, in diaclases of the slates, or over or as prismatic aggregates that are strongly striated iron oxides in cavities in the oquerous quartz. vertically, up to 1.5 centimeters in length, of white It is associated with cerussite, anglesite and more colour and a somewhat silky sheen. occasionally with atacamite and caledonite (Calvo, 2014).

Cumengeite. Microcrystals in a joint in the slates. FOV 2 mm. M. Calvo coll. Photo J. Callén. Cumengeite Microcrystals in a joint in the slates. SEM photo J. Viñals.

28 MINERAL up, Volume 5 n.1, June 18’ MINERAL up, Volume 5 n.1, June 18’ 29 Cumengeite Pb21Cu20Cl42(OH)40·6H2O They are associated with earthy iron oxides in Cumengeite has been found as light blue scoriaceous quartz cavities. In some cases, cerussite microcrystals, tetragonal bipyramidal, perfectly crystals have disappeared, leaving a spongy mass of euhedral, with {011} as the main form, modified iron oxides with the holes where these crystals were. by {001} and {110} faces, being proportionally It is also found as somewhat shiny whitish crusts larger the larger the crystals are. This is the first upholstering the surfaces of joints in the slates. deposit from which this mineral is reported in Spain.

Linarite PbCu(SO4)(OH)2 M. Calvo coll. Photo J. Callén.

Cumengeite. Microcrystals in a joint in the slates. FOV 2 mm. M. Calvo coll. Photo J. Callén. Cumengeite Microcrystals in a joint in the slates. SEM photo J. Viñals.

28 MINERAL up, Volume 5 n.1, June 18’ MINERAL up, Volume 5 n.1, June 18’ 29 Caledonite. Group of prismatic microcrystals associated to anglesite crystals. M. Calvo coll. Photo J. Callén.

Caledonite. SEM photo Morphology of a caledonite crystal. J. Viñals.

The faces of the pinacoid {100} show small parallel y Nitratos. Boratos. Escuela Técnica Superior de Ingenieros de Minas de Madrid. Fundación Gómez Pardo. 711 págs. growths. Caledonite is pale blue, transparent or -Calvo, M. (2014). Minerales y Minas de España. Vol. VI. Sulfatos translucent, brilliant, and is associated with linarite and (Seleniatos, Teluratos), Cromatos, Molibdatos y Wolframatos. Escuela anglesite in fissures in the grey slates (Calvo, 2014). Técnica Superior de Ingenieros de Minas de Madrid. Fundación The difference in color with linarite makes it very easy Gómez Pardo. 653 págs. -Guardiola, R. (1927). Estudio Metalogenético de la Sierra de to distinguish them in this paragenesis. Cartagena. Memorias del Instituto Geológico de España, 33, 564 págs. -Humpreys, D.A., Thomas, J.N. y Williams, P.A. (1980). The chemical Acknowledgmens stability of mendipite, diaboleite, chloroxiphite, and cumengeite, and We thank José Rafael González López and Agustín their relationships to other secondary lead(II) minerals. Mineralogical Magazine, 43, 901-904. Sanz Real, who have contributed some of the samples -Paillette, A. y Bezard, E. (1849). Coup d’oeil sur le gisement et la used in the analysis. composition chimique de quelques minerais de fer de la province des Asturies (Espagne). Bulletin de la Societé Geologique de France, 2ª ser., 6, 575-599

References -Calvo, M. (2003): Minerales y Minas de España. Vol II, Sulfuros y Miguel Calvo Sulfosales Museo de Ciencias Naturales de Álava, Vitoria. 705 p. Zaragoza University, Spain -Calvo, M. (2012). Minerales y Minas de España. Vol. V. Carbonatos [email protected]

30 MINERAL up, Volume 5 n.1, June 18’ MINERAL up, Volume 5 n.1, June 18’ 31 Caledonite. Group of prismatic microcrystals associated to anglesite crystals. M. Calvo coll. Photo J. Callén.

Caledonite. SEM photo Morphology of a caledonite crystal. J. Viñals.

30 MINERAL up, Volume 5 n.1, June 18’ MINERAL up, Volume 5 n.1, June 18’ 31