REPORT OF ASSISTANT SECRETARY. 179 



Liveii)()ol casos and 4 slope-top cases, and consisted entirely of choice, 

 selected characteristic material. For the time being-, of course, the 

 exhibition series in Washington was i>erceptibly weakened. 



Durin.i;- the year ."US entries were made in the catalogue of the depart- 

 ment, representing ~)7\) specimens. Of these a considerable number 

 were bought with reference to exhibition at Chicago, especially a fine 

 group of representative gems from Amelia County, Va., a superb series 

 of crystallized sulphurs from Sicily, and a suite of anglesite crystals 

 fi'om Monteponi, Sardinia. Some remarkable Sicilian selenites and 

 celestites, and the gToui)S of tiuorites from the Wilcox collection were 

 also obtained in this way. 



By gift, little was received during the year. The most notable 

 accession of this kind was a series of 7 cut turquoises and 1 specimen 

 of turquoise in the matrix,, presented by the American Turquoise Com- 

 pany, of Xew York. The exchanges also were few in nundxn". Six- 

 teen specimens of miscellaneous minerals were thus obtained from jMr. 

 E. E. Howell, and 51 sj)ecimens, all of European origin, were received 

 from Prof. P. Groth, of Munich, in return for a collection previously 

 sent to him. Still another exchange collection came from Prof. A. 

 Brezina, of Vienna, but it was not catalogued during the year covered 

 by this report. 



When the (;ollections now in Chicago shall have been returned to 

 Washington, the incorporation of the new material obtained into the 

 permanent series will involve a general reorganization of the exhibition 

 hall. Much old nmterial will be retired to the study and duplicate 

 series, to make room for new and finer specimens. Until that work 

 has been done, no satisfactory census of the mineral collection can be 

 made. 



The last catalogue entry of the preceding year, June 30, ISOli, was 

 No. 80()40. The last entry of the present year, June 30, 1893, is ^o. 

 80991. 



KXIIIUIT OF MINKKAL.S AT THE WOKLD'S COLUMBIAN EXrOSITIOX. 



The exhibit consisted of minerals, gems, and semi-precious stones, 

 illustrating the principles of crystallography and those physical prop- 

 erties of minerals which apply to the eye, and included the following 

 series : 



Crystallography and the physical projierties of minerals. 



A series of crystallized minerals (with the i)riiicip:il forms in models of wood) to 

 illnstrate crystal form. 

 A series to illustrate ]>arallel growtlis. 

 A series to illustrate the twinning of crystals. 

 A series to illnstrate the imperfections of crystals. 

 A series of crystalline aggregates. 

 A series of pseudoniori>hs. 

 A series to illustrate structure. 

 A series to illustrate cleavage and fracture. 

 A series to illustrate diaphaneity, color, and luster. 



A collection of gems and semi-precious stones, embracing two series, as fcdlows: 

 A general series, arranged in the order of their intrinsic value. 

 A series of American gems and semi-precious stones. 



