THE COLLECTION OF MINERALS 
Some of the haloids, as exemplified by the mineral halite or rock 
salt, the chloride of sodium, occur in nature in extensive beds and have 
been deposited by evaporation from bodies of water which have in 
times past been cut off from the main body of the ocean. The series 
of halite specimens in Case 3 includes many striking examp!es of large 
and well-developed crystals. 

MARCASITE FROM FELSOBANYA, HUNGARY 
A radiated aggregate of flat crystals 
The most widely distributed mineral in this division is fluorite, the 
fluoride of calcium. This is essentially a vein mineral and is frequently 
found associated with the sulphide ores of lead and zine. The large 
cubic and octahedral crystals of fluorite from all parts of the world 
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