Barytocalcite [SEP] named after
Barytocalcite
Barytocalcite is an anhydrous barium calcium carbonate mineral with the chemical formula BaCa(CO). It is trimorphous with alstonite and paralstonite, that is to say the three minerals have the same formula but different structures. Baryte and quartz pseudomorphs after barytocalcite have been observed.
Barytocalcite crystallizes in the monoclinic crystal system, typically as massive to druzy accumulations of transparent white to yellow to grey aggregates of slender prismatic crystals. It has a Mohs hardness of 4 and a specific gravity of 3.64 to 3.71.
It was first described in
Alstonite
Alstonite, also known as bromlite, is a low temperature hydrothermal mineral that is a rare double carbonate of calcium and barium with the formula , sometimes with some strontium. Barytocalcite and paralstonite have the same formula but different structures, so these three minerals are said to be trimorphous. Alstonite is triclinic but barytocalcite is monoclinic and paralstonite is trigonal. The species was named bromlite by Thomas Thomson in 1837 after the Bromley-Hill mine, and alstonite by August Breithaupt of the Freiberg Mining Academy in 1841, after Alston,