Minium, or Red Lead

a lead oxide mineral from the southwestern United States


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Above: A west- to -east section looking north through the Leadville district, 8.6 km long, from Emmons (1882).

Two small samples in my collection are:

a) sample 1442, minium with jarosite from Leadville, Lake county, Colorado (ex-David New). Brilliant red minium with grey quartz and bright yellow jarosite. This little sample is just 40x35x23 mm in maximum dimensions but feels very dense at 51.41 grams: there is relict fine-grained granular galena within the oxide. The jarosite is late, in veinlets that crosscut both the primary ore and the secondary Pb oxide. The sample is not appreciably magnetic, bulk magnetic susceptibility <0.03x10-3 SI units.

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and

b) BELOW: two complementary views of sample 1885, minium on cerussite, from the Tonopah-Belmont mine, Maricopa county, in west-central Arizona (ex-David Shannon). Dense, pale brownish cerussite with minor malachite and perhaps other green Cu salts, invested with powdery bright orange minium. The sample weighs 48.92 grams, is a maximum of 53x35x20 mm in size, and displays magnetic susceptibility <0.02x10-3 SI units. The sample has a solid heft for its size, and the interior is likely an altered Tertiary volcanic rock of (?) andesitic composition. The mine's geology and mineralogy are described by Allen and Hunt (1988). Minium, as a secondary salt, formed near the end of the paragenesis, the sequence of crystallization of minerals, that began with primary sulphides such as galena (PbS), chalcopyrite and sphalerite, plus gold and silver as native elements. The late secondary minerals include minium, calcite, gypsum and hydrozincite. Minium is reported to form bright red pseudomorphs after cerussite (PbCO3) on willemite (a zinc silicate), but the material shown here appears to be the more typical late crust.

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"Rock of the Month #113, posted for November 2010" ---

Minium, better known as red lead is a seldom-recognized lead oxide mineral, formula Pb2+2Pb4+O4, also obscurely known as miniumite or minio (Clark, 1993, p.461). Long ago the name minium was applied to a more famous red mineral, cinnabar, the lead oxide being an adulterant in the mercury sulphide (Blackburn and Dennen, 1997, p.200). Related phases include two polymorphs of PbO, massicot and litharge. It is said (Pough, 1996, pp.144-145) that masses of minium at Broken Hill, New South Wales, Australia, formed by the roasting of cerussite ore, may be some of the best material available, albeit a "man-made mineral", not exactly nature's own...

Minium is most often found in lead deposits with abundant secondary, oxidized mineral species. Examples are Leadville, Colorado (Emmons, 1882), the South Mountain district of Idaho (Sorensen, 1927), and Ojuela, Durango (Moore and Megaw, 2003). Panczner (1987) provides a short list of minium occurrences in 7 states of Mexico, including the Lomo del Toro mine in Zimapan, Hidalgo.

In the Leadville mining camp, the principal ore mineral in the early days was argentiferous galena, supplemented by cerargyrite, anglesite and cerussite, plus pyromorphite, litharge, minium and other minerals (Emmons, 1882).

Minium has also been reported from other base-metal mining areas, including Tintic, Utah (Tower and Smith, 1899) and Parys Mountain in Wales (Plant et al., 2011). Minium has also been found in slags and related wastes of the Laurium (Laurion) mines of Greece (Mishara, 1989; Gelaude et al., 1996). Another ancient mining site which is a minium occurrence is Kuhne Mes in southern Iran (Haynes, 1989). Although uncommon, it is described in a number of popular mineralogy texts, such as Pough (1970) and Bauer and Tvrz (1974).

Little recent research seems to have been done, though McConachy et al. (2007) include minium in a cataloguing of spectral reflectance data, with potential for the exploration for oxidized (non-sulphide) base-metal deposits.


References

Allen,GB and Hunt,W (1988) The Tonopah-Belmont mine, Maricopa county, Arizona. Mineral.Record 19, 139-144.

Bauer,J and Tvrz,F (1974) A Field Guide in Colour to Minerals, Rocks and Precious Stones. Octopus Books Ltd, London, Engl. translation, 208pp.

Blackburn,WH and Dennen,WH (1997) Encyclopedia of Mineral Names. Canadian Mineralogist Spec.Publ. 1, 360pp.

Clark,AM (1993) Hey's Mineral Index. Natural History Museum / Chapman and Hall, London, 852pp.

Emmons,SF (1882) Geology and mining industry of Leadville, Lake county, Colorado. USGS 2nd Annual Report, 55+588pp., 201-290.

Gelaude,P, van Kalmthout,P and Rewitzer,C (1996) Laurion: The Minerals in the Ancient Slags. Janssen Print, Nijmegen, Netherlands, 194pp. (in Engl., in Ger., in Fr. and in Dutch).

Haynes,SJ (1989) Kuhne Mes, Southern Iran: a Tertiary sabkha-hosted Cu-Pb deposit associated with active compressional tectonics. In `Sediment-Hosted Stratiform Copper Deposits' (Boyle,RW, Brown,AC, Jefferson,CW, Jowett,EC and Kirkham,RV editors), GAC Spec.Pap. 36, 710pp., 637-646.

McConachy,TF, Yang,K, Boni,M and Evans,NJ (2007) Spectral reflectance: preliminary data on a new technique with potential for non-sulphide base metal exploration. Geochemistry: Exploration, Environment, Analysis 7, 139-151.

Mishara,J (1989) The plasters of the ore washing structures at Laurion. In `Archaeometry' (Maniatis,Y editor), Proc. 25th International Symposium on Archaeometry, Elsevier, 718pp., 191-205.

Moore,TP and Megaw,PKM (2003) The Ojuela mine, Mapimi, Durango, Mexico. Mineral.Record. 34, 5-91.

Panczner,WD (1987) Minerals of Mexico. Van Nostrand Reinhold Co., 459pp., pp.275-276.

Plant,SP, Cotterell,TF and Starkey,RE (2011) Anglesite from the type locality, Parys Mountain, Anglesey, Wales. Mineral.Record 42, 345-384.

Pough,FH (1970) A Field Guide to Rocks and Minerals. Constable, London, 2nd edition, 349pp., 1960, republished in UK.

Pough,FH (1996) A Field Guide to Rocks and Minerals. Houghton Mifflin Company, Peterson Field Guides, 5th edition, 396pp.

Sorensen,RE (1927) The Geology and Ore Deposits of the South Mountain Mining District, Owyhee County, Idaho. Idaho Bureau of Mines and Geology Pamphlet 32, 47pp.

Tower,GW and Smith,GO (1899) Geology and mining industry of the Tintic district, Utah. USGS 19nd Annual Report, Part III - Economic Geology, 601-767.

Graham Wilson, 14 and 22/25 July 2011, Tonopah-Belmont note, photos and Mexico notes added 12,16,20-23 January 2013

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