Barytocalcite

minerals

alstonite

witherite

baryte

Formula: BaCa(CO3)2
Anhydrous normal carbonate, the monoclinic paramorph of alstonite (triclinic) and paralstonite (trigonal). Barytocalcite is epitaxial on baryte, and calcite is epitaxial on barytocalcite (Dana ).
Baryte and quartz pseudomorphs after barytocalcite have been observed (Mindat).
Specific gravity: 3.66 to 3.71
Hardness: 4
Streak: White
Colour: Colourless, white, greyish, greenish, light yellow
Solubility: Soluble in dilute hydrochloric acid
Environments

Carbonatites rarely
Metamorphic environments
Hydrothermal environments

Barytocalcite is a relatively uncommon accessory mineral in metallic veins, formed by reaction of hydrothermal fluids with limestone, although it may be the dominant barium-bearing species; it occurs rarely in carbonatites and Alpine veins. Associated minerals include baryte, calcite, strontianite, siderite, alstonite, benstonite, witherite, norsethite, fluorite, sphalerite, pyrrhotite and quartz (HOM).

Localities

At the Tolecheinski deposit, Krasnoyark region, Siberia, Russia, barytocalcite occurs in baryte ore (Dana).

At Långban, Filipstad, Värmland County, Sweden, barytocalcite occurs with hedyphane and hausmannite (Dana).

At the type locality, the Blagill Mine, Alston Moor, Eden, Cumbria, England, UK, barytocalcite occurs in veins in limestone associated with fluorite, calcite and baryte (Mindat).

In the Alston block of the Northern Pennine Orefield, England, UK, barytocalcite is widely distributed. it is usually associated with witherite (JRS 17.43.

At Brownley Hill, Nenthead, Alston Moor, Eden, Cumbria, England, UK, barytocalcite has been found in minute traces epitaxial on nailhead calcite, commonly associated with alstonite. Barytocalcite and alstonite both crystallise after calcite, and it appears probable that barytocalcite is earlier than alstonite (Minrec 31.3.242-243).

At the Rorrington mine, Chirbury, Shelve, Shropshire, England, UK, barytocalcite has been found in a cavity in baryte-witherite veinstone (RES 287).

The Holwell quarry, Broomfield, Somerset, England, UK, is the only locality in the Mendips where barytocalcite had been conclusively identified by 1990. It occurred in a single small area as aggregates small platy crystals within calcite lined vugs in manganese oxides (JRS 13.17).

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