fluor-spar Min.
(ˈfluːəspɑː(r))
[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, 3{supd} Family, Foliated or sparry, Fluor spar. 1812 Sir H. Davy Chem. Philos. 465 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. |