170 ACCOUNTS, ETC. OF THE BRITISH MUSEUM. 



Department of Mineralogy. 



Research. 



During the year the crystallographie and chemical investi- 

 gation of new and rare minerals, belonging to the Sulphide 

 Division, from the Binnenthal, Switzerland, has been con- 

 tinued. In this connection crystals of smithite, hutchinsonite, 

 trechmannite, marrite and lengenbachite have been crystallo- 

 graphically and optically studied ; and quantitative chemical 

 analyses have been made of smithite and hutchinsonite, one 

 result of which has been to show that the rare element 

 thallium is an important constituent of the latter mineral. 

 In the Halide Division the new mineral paratacamite has 

 been further crystallographically examined and the nature of 

 its complex twinning discussed. In the Silicate Division an 

 investigation has been in progress into the range of variation 

 of the physical characters of the garnets, and for this purpose 

 the refractive indices and specific gravities of various faceted 

 stones have been determined. 



A collection of minerals from German East Africa, includ- 

 ing a fine specimen of phenacite, has been crystallographically 

 investigated. 



Various minerals (including specimens of andorite,stannite, 

 tourmaline and wolframite) from Bolivia have also been ex- 

 amined and determined. 



Crystallographie measurements have been incidentally 

 made on various other specimens, including albite, anatase, 

 apatite, blende, calaverite, caracolite, ilmenite, krennerite, 

 parisite, seligmannite, sylvanite, tennantite and^turnerite. 



The petrographical examination of the 9C0 rock- specimens 

 collected in the course of the "Discovery " Antarctic Expedi- 

 tion has been in progress. In this connection about .300 thin 

 slices have been microscopically examined, six quantitative 

 chemical analyses have been made, and specimens of salts 

 found on Antarctic ice have been qualitatively analysed. 



Specimens of dundasite from North Wales, a mineral 

 which hitherto has been found only in Tasmania, have been 

 examined and determined ; and a chemical formula for the 

 mineral has been for the first time determined by a quantita- 

 tive chemical analysis. 



In the chemical laboratory 12 complete quantitative 

 analyses have been made, viz., of smithite (2), hutchinsonite 

 (2), Antarctic rocks (6), a doubtful mineral from Ceylon 

 containing rare-earths (\), and dundasite (1). Further, 34 

 doubtful minerals have been qualitatively analysed. 



