156 A POPULAR EXPOSITION OF THE 
cleavage, and the regular octahedron (Fig 48 @) may thus be obtained 
from them. Specimens occur of all colours, 89 4 
but chiefly, dark violet-blue, lilac, yellow, pea KS 
green, white, and grey: the edges of the - aa 
crystals being often of a deeper or lighter \, | | 
shade, or even of a different colour, from the i a 
central parts. Streak, white. H. 4-0; sp. To es 
gr. 31-32. Fusible before the blowpipe Wi 
into a white enamel, but most specimens de- ith ZL 
crepitate on the first application of the flame. Fig. 48. 
(See Part I., Vol. V., pp. 17-18). When 
crushed to a coarse powder and gently heated, a greenish or other 
coloured phosphorescence is usually exhibited. Composition : fluorine 
48-7, calcium (the metallic base of lime) 51:3. Fluor spar oceurs in 
some of the crystalline limestones of our Laurentian rocks; and 
here and there in the metalliferous veins of the Huronian formation ; 
also, in small cavities in the limestones of the Silurian series. The 
best known localities comprise Fluor Island in Prince’s Bay, on the 
north shore of Lake Superior, where fine green crystals occur ; Iron 
Island on Lake Nipissing, where blue crystals were discovered by Mr. 
Murray*; the township of Ross in Renfrew County, on the Ottawa; 
the Niagara limestone about the Falls, &c. In Europe, fluor spar 
oceurs, more especially, in association with lead, tin, and silver ores, 
in metallic veins. 
Heavy Spar or Sulphate of Baryta.—White, grey, yellow, reddish, 
etc., with white or uncoloured streak. In lamellar, laminar, and 
fibrous masses ; and also in trimetric crystals, of which a common 
example is given in figure 49. H. 3:0-8°5 ; sp. gr. 
4°3-4°7. Decrepitates (in general) before the blow- 
pipe, (see Parr I., Vol. V., p. 17-18), and fuses ae 
into a white enamel, tinging the point of the flame 
pale green. This latter character is well-marked, 
and serves to distinguish, very readily, small pieces 
of heavy spar from other minerals of a similar 
aspect. With carbonate of soda in the yellow flame, it forms an 
alkalme sulphide, which imparts, when moistened, a dark stain to 
Fig. 42 
*See Canadian Journal, Vol. 111, New Series, p. 325. Also Geological Report for 1854- 
The crystals occur in crevices and fissures of a cavernous limestone associated with specular 
iron ore. 
