Minerals and Gems 61 



the north wall, are inscribed to indicate the presentation of 

 the Morgan Hall by Mr. Baker in memory of his friend Mr. 

 Morgan, and with the names of donors of mineral and gem 

 specimens which have materially enhanced the collections. 



The occasion of the reception tendered to Madame Curie 



at the Museum was marked by a temporary exhibit of the 



sources of radium and its utilization in surgery. 



Special The D epartment contributed to this exhibit 



Exhibits v p T 



specimens of radioactive minerals. In many in- 

 stances these were accompanied with a radiograph showing 

 the action of the specific mineral upon a photographic plate. 

 This installation, which was on exhibition for three months 

 in the Southwest Wing of the first floor, aroused much popu- 

 lar interest. 



During the Summer Session at Columbia University, the 

 Curator delivered a course of lectures and conducted con- 

 ferences on Gems and Gem Minerals; the con- 

 st ension ference hours were held in the Morgan Hall of 

 Gems. The lantern slides illustrating these 

 lectures were made largely from specimens in the Tiffany 

 Collection, presented by Mr. Morgan, and are now available 

 for subsequent popular lectures on Gems. 



The research laboratory has added to its equipment a Leitz 

 Petrographic Microscope, Model C. M., for the determination 

 of minerals in minute crushed fragments. Work 

 upon a crystallographic atlas of the Mineral 

 Collection was begun in the summer with a detailed study of 

 several occurrences in the division of the metallic sulphides. 

 Satisfactory crystallographic measurements were made on a 

 number of highly interesting specimens in the pyrite series, 

 resulting in the discovery of several new forms. 



Notable among the gifts to the Mineral Collection are a 



very complete series of the copper minerals from the Braden 



Mines at Rancagua, Chile, and a fine suite of the 



Accessions 



copper and iron sulphides from Chuquicamata, 

 Chile, presented by Mr. Harry F. Guggenheim. The first of 

 these donations is important in that it represents the mineral 

 phases of the Rancagua deposit by genetic zones in great de- 

 tail and completeness, and it is also rich in fine specimens of 



