THE NONMETALLIC MINERALS. 



213 



Composition of salt from various localities Continued. 



2. FLUORITE. 



This is a calcium fluoride, CaF 2 = fluorine 48.9 per cent, cal- 

 cium 51.1 per cent. The most striking features of this mineral are its 

 cubic crystallization (Specimens Nos. 51226, 66831, 66832, U.S.N.M.), 

 octahedral cleavage (Specimen No. 48270, U.S.N.M.), and fine green 

 (Specimen No. 48270, U.S.N.M.), yellow (Specimen No. 49160, 

 U.S.N.M.), purple (Specimen No. 51226, U.S. N.M.), violet, and 

 sky blue colors. White (Specimen No. 36091, U.S.N.M.) and red- 



