Barytocalcite Locality: Blagill Mine, Nent Valley, Alston Moor District, North Pennines , North and Western Region (Cumberland), Cumbria , England , UK ( Locality at mindat.org ) Size: 8.6 x 7.7 x 3.7 cm. A fine specimen of bladed barytocalcite from the Type Locality- the only mine in the world where barytocalcite has been mined as an ore. This is a large specimen with unusually large and isolated crystals, shooting up in every direction on the matrix. The grayish-white blades have a matte lustre. Ex. Richard Barstow Collection, a very well-known English dealer and collector, who personally collected this piece. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Barytocalcite
A barium-calcium carbonate that shares its formula with alstonite and paralstonite but crystallizes differently.
Intro adapted from Wikipedia (CC BY-SA).
Barytocalcite is an IMA-recognized mineral species in the carbonate class, with the chemical formula BaCa(CO₃)₂.
It crystallizes in the monoclinic crystal system (space group P2_1).
Key properties: Mohs hardness 3.5–4; specific gravity 3.66–3.71; Vitreous to resinous luster; refractive index 1.632; optically biaxial.
IMA symbol Bcal, grandfathered status — known before the IMA’s founding, named in 1824.
A relatively uncommon accessory mineral in metallic veins, formed by reaction of hydrothermal fluids with limestone; however it may be the dominant barium-bearing species; rarely in carbonatites and Alpine veins.
It is found associated with Barite, calcite, strontianite, siderite, alstonite, benstonite, witherite, norsethite, fluorite, sphalerite, pyrrhotite, quartz.
The name refers to barium with calcium and carbonate (calcite) in its composition.