PREFATORY NOTE. 



In the annual report of the United States National Museum for 

 1900 (1902) there was published a descriptive catalogue of the col- 

 lections of gems in the United States National Museum, as prepared 

 by Mr. Wirt Tassin, then assistant curator in charge of the Division 

 of Mineralogy, assisted by A. S. Eakle, subsequently professor of 

 mineralogy in the University of California. As this catalogue has 

 long been out of print, and as the collection has increased consider- 

 ably since it appeared, a new edition has been decided upon. In 

 this, however, a different method of treatment has been adopted, 

 and the subject matter has been quite largely rewritten, so that it 

 represents an essentially new work. 



In order that just credit may be given to all concerned it may be 

 well to state that the preparation of the catalogue was begun in 1916 

 by Dr. Edgar T. Wherry, then assistant curator in charge of the 

 mineralogical collection. His resignation in 1917 caused a long de- 

 lay, and meanwhile, during the occupancy of the building by the War 

 Risk Bureau (October, 1917, to March, 1919), it was decided to en- 

 tirely rearrange and recatalogue the collection which had been 

 heretofore included with the general collection of minerals. This 

 work, which involved as well the weighing and measuring of each 

 individual stone, has been slow and laborious, but has been carried 

 through in almost its entirety by Miss Margaret W. Moodey, the re- 

 corder for the department. In preparing the text so much of the 

 edition of 1902 as was suitable has been retained (see particularly pp. 

 141-178), to which has been added the descriptive matter prepared by 

 Doctor Wherry. Important additional matter is furnished in the 

 accounts of the pegmatites and their associated minerals, that of 

 southern California having been prepared by Dr. W. T. Schaller, for 

 several years custodian of the collection. Other important additions 

 are the references to the Gardner Williams collection of rocks from 

 the diamond mines of South Africa, the list of gem names and the 

 table for the identification of precious stones. 



In addition to portraits of the founder and benefactor of the col- 

 lection, and two colored plates illustrating gems in the collection, 

 there have been added a number of plates showing typical localities 

 from which gems are mined. 



George P. Merrill. 



IV 



