Witherite

witherite

barytocalcite

alstonite

baryte

Images

Formula: Ba(CO3)
Anhydrous normal carbonate, barium mineral, aragonite group Witherite is epitaxial on barytocalcite and baryte is epitaxial on witherite (Mindat)
Specific gravity: 4.289 to 4.293
Hardness: 3 to 3½
Streak: white
Colour: colourless, white, pale yellow; colourless in transmitted light
Solubility: Readily soluble in hydrochloric acid; moderately soluble in sulphuric and nitric acids
Common impurities: Ca, Sr
Environments:

Hydrothermal environments

Witherite occurs typically, along with baryte and other barium-bearing minerals, in epithermal (low temperature) hydrothermal mineral veins, usually resulting from the alteration of baryte (HOM). Other commonly associated minerals include calcite, alstonite, sphalerite and galena.

Localities

At the type locality, the Brownley Hill mine, Nenthead, Alston Moor, Eden, Cumbria, England, UK, witherite is associated with alstonite, calcite, hydromagnesite, galena, pyrite and marcasite (Minrec 31.3.248).

At the Nentsberry Haggs mine, Alston Moor, Eden, Cumbria, England, UK, witherite is often encrusted with baryte and/or calcite, sometimes associated with altered alstonite (JRS 17.47-48). Witherite has also been found on galena and dolomite, sometimes partly altered to baryte (SY p174).

At the Hilton mine, Scordale, Murton, Eden, Cumbria, England, UK, baryte pseudomorphs after witherite have been found (Minrec 41-1 Supplement p109).

At the Fallowfield Mine, Acomb, Northumberland, England, UK, fine specimens of witherite are found, often coated with a dusting of baryte and occasionally found intergrown with alstonite (Minrec 41-1 Supplement p102, SY p174).

At Snailbeach mine, near Minsterley, Shropshire, England, UK, witherite occurs impregnated with hydrocarbon and overgrown by baryte (RES p271, 274).

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