NATURAL HISTORY MUSEUMS 35 



tificially colored agates from South America; among the car- 

 bonates, curiously distorted calcite crystals from Egremont 

 Eng. and the flos ferri aragonites; among the silicates, large 

 crystals of Amazon stone from Pike's Peak, OoL, and the trans- 

 parent and perfect crystals of topaz from Siberia; among the 

 phosphates, the richly colored vanadinites from Arizona; and 

 among the sulfates, the brilliant groups of celestite from Sicily. 



In addition to these the museum contains the Higinbotham 

 collection of gems and gem minerals, one of the most valuable 

 in the world. The Chalmers crystal collection contains about 

 200 specimens from the United States. 



The collection of meteorites includes over 230 " falls " or 

 " finds ", represented by 5000 specimens having an aggregate 

 weight of 4745.6 pounds, and 63 casts or models of notable 

 meteorites. The specimens are divided into three classes, viz, 

 siderites, siderolites and aerolites, and are arranged chrono- 

 logically. 



Structural and dynamic geology. 1500 specimens illustrating 

 dendrites, volcanic products, cave products, varieties of rock 

 structure, concretionary structure, and rock texture. A real- 

 istic reproduction of a limestone cave, in which about 100 speci- 

 mens of stalactites and stalagmites are mounted in their natural 

 position and with proper accessories, is an important feature 

 of the exhibit. 



Economic geology. 10,000 specimens, probably the largest and 

 most complete of the kind in the world, illustrating modes of 

 occurrence in nature of the minerals and ores of economic 

 importance. Nearly all the important mining districts of the 

 world are represented by typical specimens. Specially complete 

 series are: mineral oils of the United States and their products, 

 coals of the United States, platinum ores, zinc ores of the United 

 States, marbles and clays. Ores of gold, silver, lead, copper, 

 iron, zinc, mercury, nickel, and the rarer metals are also fully 

 illustrated, many of the specimens being of great size and of a 

 high degree of perfection. A full sized statistical column origi- 

 nally prepared by the United States geplogical survey, illus- 



