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|Colour:||Black, bluish black, ...||Hardness:||1 - 6½|
|Name:||Wad, wadd, and/or wadt were used as early miner's terms and used for various black mineral substances. The redundant name "black wad" has been frequently attributed to Richard Kirwan in his Elements of Mineralogy (1784) but Kirwan mentioned, but did not cite, neither Josiah Wedgwood's (1783) analysis of "black wadd" nor contemporary experiments with wad by Joseph Banks, nor any earlier sources. (Wad had the unusual oxidizing power of causing an equal mixture of it and linseed oil to combust after an hour or two.) Kirwan did describe the material: "One of the most remarkable ores of manganese is that called black wad; it is of a dark brown colour, partly in powder and partly indurated, and brittle." Earthy wad-like manganese minerals, of course, were used in glass making in ancient Rome and wads were used as pigments in prehistoric times. (Manganese metal was first isolated in impure form in 1774.) According to Thomas Robinson (1709), wad was also used relating to graphite by miners in the Westmoreland and Cumberland (Cumbria) regions of England. Robinson (1709) further indicated that the name "wadt" was used in Germany suggesting the black character of a substance. Jonathan Otley (1819) stated that a deed dated November 28, 1614 in Borrowdale, England referred to graphite as wad: "... the several names of wad, black cawke, black lead, plumbago and graphite, by which this mineral has been successively designated..."|
|A Mixture Of:||Manganese Oxides|
A generic name for (often poorly crystalline) soft manganese oxides/hydroxides, often containing significant amounts of hydroxides/oxides of other metals and adsorbed metals (Ni, Co, Cu, Fe, and other transition metals, alkali elements, etc.)
See also Manganese Oxides.
Classification of Wad
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Physical Properties of Wad
|Colour:||Black, bluish black, brownish black|
|Streak:||Black, bluish black, brownish black, reddish brown, liver-brown|
|Hardness (Mohs):||1 - 6½|
|Density (measured):||2.8 - 4.4 g/cm3|
Other Names for Wad
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Wad
Robinson, Thomas (1709) An Essay Towards a Natural History of Westmoreland and Cumberland, Freeman, pp 95.
Wedgwood, Josiah (1783) Some Experiments upon the Ochra Friabilis Nigro Fusca of Da Costa... and called by the Miners of Derbyshire, Black Wadd, Philosophical Transactions of the Royal Society of London, p. 284-287.
Otley, Jonathan (1819) Account of the Black-Lead Mine in Borrowdale Cumberland, Memoirs of the Literary & Philosophical Society Manchester, v. 3 series 2, p. 168-175.
Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 566-567.
Internet Links for Wad
Localities for Wad
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