THE COLLECTION OF MINERALS 
Garnet, Idocrase, Quartz, Mica, Gypsum, Corundum and Spinel, 
have been so long in use that, like the names of the metals and 
elements, they must be retained. 
According to chemical composition, therefore, the following 
principal subdivisions of minerals have been established: 
I. The Native Elements. 
II. The Arsenides, Sulphides, Antimonides, Sulph-arsenides, 
Sulph-antimonides and similar compounds. 
Ill. The Haloids. 
IV. The Oxides, anhydrous and hydrous. 
V. The Oxygen-salts, such as Carbonates, Silicates, Phos- 
phates, Columbates, Tantalates, Sulphates and Nitrates. 
VI. The Hydrocarbons. 
This system is almost universally used to-day, with changes, 
however, more or less material in the succession and interpreta- 
tion of its various parts, and is practically the production of the 
last century. = 
Owing to the early activity of chemical agencies and the still 
continuing energy of oxygen, a gas which is constantly attacking 
uncombined elements, the list of Native Elements, as at present 
known, is much shorter than the list of elements known to chem- 
istry, a large number of them heing precluded from any inde- 
pendent existence whatever through their strong affinities for 
other substances. The mineralogist finds, however, in the 
portions of the earth accessible to him, a small list of native ele- 
ments, of which six, at the most, are characteristically uncom- 
bined, while the remainder, about fifteen in number, are found 
native only under exceptional conditions, and one of them, iron, 
is particularly interesting because its most frequent occurrence 
is in the form of meteorites. 
GUIDE TO THE COLLECTION. 
The collection of minerals is exhibited in two halls on the 
fourth floor of the Museum, marked “A” and “B”’ on the dia- 
gram, and is displayed in two sections, the wall case and the desk 
case exhibits. The wall cases contain those specimens which are 
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