3/8 FLUOR SPAR. 
of lead. Veins of a considerable thickness are often 
almost entirely filled with this substance, of which 
the masses present an assemblage of the most lively 
and opposite colours, the effect of which is very 
much heightened by streaks of metal passing 
through the fluor in different directions. All the 
crystallizations which are found in metallic veins, 
and especially the groups of fluor spar, are subject 
to an accident which is worthy of attention : it is, 
that their surface is sometimes studded with a mul- 
titude of marcasites, pyrites, or grains of galena, but 
always on the lower side, or that which is directed 
towards the bottom of the mine. 
M. Patrin observes, that the fluor spar which is 
found mixed with the primitive rocks, is generally 
either in masses or veins without being of any de- 
terminate figure ; nevertheless, M. Pictet of Geneva 
has described a fluor spar of a rose colour, formed 
of crystals of eight sides, which he brought from a 
rock near the bottom of a glacier, in the valley of 
Chamouny. The crystals are an inch in diameter, 
and of a uniform size, in all the pieces observed by 
M. Pictet. He adds, that similar specimens are to 
be found in Mount Saint-Gothard, but that they are 
of a smaller size. 
It is singular, that although this mineral is plen- 
tiful in several parts of Europe, yet it is rare in the 
other quarters of the world. Among the numerous 
specimens of fluor spar which have been described 
by Rome de l’lsle, who has paid great attention to 
