Barytocalcite
From LoveToKnow 1911
BARYTOCALCITE, a rare mineral found only at Alston Moor in Cumberland, where it occurs as diverging groups of white transparent crystals lining cavities in the Mountain Limestone.
c d d FIG. 3.
The crystals belong to the monoclinic system and are usually prismatic or blade-shaped in habit. The hardness is 4, and the sp. gr. 3.65. There are perfect cleavages parallel to the prism faces inclined at an angle of 73° 6', and a less perfect cleavage parallel to the basal plane, the angle between which and the prism faces is 77° 6'; the angles between these three cleavages thus approximate to the angles (74 0 55') between the three cleavages of calcite, and there are other points of superficial resemblance between these two minerals. Chemically, barytocalcite is a double salt of barium and calcium carbonates, BaCa(CO 3) 2, thus differing from the orthorhombic bromlite which is an isomorphous mixture of the two carbonates. (L. J. S.)
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