AMERICAN MUSEUM GUIDE LEAFLETS 
luster almost identical to stibnite, the antimony sulphide; and many 
of the ores of the metals, such as smithsonite, the carbonate of zinc, and 
malachite, the carbonate of copper, show a luster which is not at all 
metallic. Minerals do, however, possess a property which is very useful 
in identifying them. With very few exceptions every mineral species 
has a more or less pronounced tendency to form in solids with regular 
outlines, smooth bright faces and sharp angles. These solids which are 
called crystals are distinctive, each mineral having its characteristic 
series of forms, some occurring in cubes, others in slender needle-like 
prisms, and others in flat angular plates. Although the very great 
diversity and intricacy of these crystal forms of minerals are somewhat 
bewildering to anyone unfamiliar with this highly fascinating branch of 
science, one soon finds that they are capable of being divided into a 
small number of very simple groups. A series of models showing some 
of the more important forms of crystals and their relation and meaning 
will be found to the right of the entrance to the Mineral Hall. 
THE HISTORY OF THE COLLECTION 
Like most of the large mineral collections of the world, the collection 
displayed in the Morgan Hall of Minerals has been the result of slow 
growth over a considerable period. The nucleus of the present collec- 
tion was the Bailey Collection, a relatively small series of the commoner 
minerals, but one which was thoroughly comprehensive and served well 
in the early days of the Museum to represent this branch of Science. 
The first large addition came in 1891, when the Spang Collection was 
purchased and not only more than doubled the number of specimens in 
the Museum but added many new species to those already displayed. 
It was in 1900, however, that the Collection took rank as the most com- 
plete as well as the richest in notable specimens in America and one of 
the five best exhibition collections in the world. Through the gift of 
the late J. Pierpont Morgan, Esq., the Museum acquired the remark- 
able collection of minerals brought together by Mr. Clarence 8. Bement. 
of Philadelphia. This last addition, which comprises a large percentage 
of the specimens now displayed in the Morgan Hall of Minerals, is 
famous for the exceptional perfection of the material comprising it. 
The quality of this material, both from the point of view of its scientific 
interest and the size and beauty of its examples, may be best understood 
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