Min. [f. FLUOR + SPAR.] Native fluoride of calcium (Ca F2); found abundantly in Derbyshire (where one variety is known as Blue John), and hence often called Derbyshire spar.
1794. Kirwan, Min., I. 127. 3d Family.—Foliated, or Sparry.—Fluor Spar.
1812. Sir H. Davy, Chem. Philos., 465. There is a substance found abundantly in nature called fluor spar; it is usually either blue, green, yellow, or white, transparent, and crystallized in cubes.
1880. Ansted, Minerals, 18. The crystal of fluor-spar has the striæ parallel all round the four sides, and these are at right angles to those at top and bottom.
