
THE COLLECTION OF MINERALS 
Two kinds of native carbon, diamond and graphite, will be found in 
Case A. These are widely different in appearance and properties and 
illustrate the way in which, under different conditions of formation, the 
same chemical substance may yield dissimilar modifications. The 
beautiful groups of yellow sulphur crystals furnish the first glimpse of 

PYRITE FROM CENTRAL CITY, COLORADO 
Group of cubic crystals 
the wonderful intricacy and symmetry of the crystal forms of minerals 
(compare with model in Case M). Sulphur is formed near active or 
extinct voleanoes and in the beds of gypsum, where it constitutes a 
decomposition product. The native metals are represented by gold in 
nuggets, veins and crystal aggregates, silver in wire-like and branching 
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