144 ACCOUNTS, ETC., OF THE BRITISH MUSEUM, 



In this connection a crystallographic and chemical research 

 has been made on minerals from Bolivia, containing the rare 

 element Germanium, and has established the specific identity 

 of the so-called " Crystallised Brongniardite " with " Stan- 

 niferous Argyrodite." 



A similar research has been made on the sulph-antimonites 

 of lead belonging to the Plagionite-Semseyite group of 

 minerals. In another Mineralogical Division, the species 

 Atacamite, Laurionite, Fiedlerite, Cromfordite, Cryolite, 

 Chiolite, Thomsenolite, Pachnolite, and Ralstonite, have been 

 under investigation ; for two of them, namely, Atacamite and 

 Laurionite, the optic axial angles and the principal indices of 

 refraction have been determined for the first time ; these 

 optical constants have likewise been determined for the 

 bromo- and iodo-analogues of Laurionite, which have been 

 lately artificially produced by Baron A. de Schulten, of 

 Helsingfors, and of which specimens have been presented by 

 him to the Museum. 



A crystallographic and chemical examination has been 

 made of various iodides of silver and copper from the Broken 

 Hill Mines, New South Wales ; one of them (Miersite) has 

 been shown to be a new species of silver iodide. 



Optical examinations have also been made of specimens of 

 Thomsonite and Stilbite in connection with a critical investi- 

 gation of the mineral termed " Sphserostilbite." 



Crystals of the following species have been incidentally 

 measured : — Anglesite, Augelite, Barytes, Binnite, Blende, 

 Boulangerite, Calcite, Cassiterite, Cerussite, Copper Pyrites, 

 Diaphorite, Freieslebenite, Galena, lodyrite, Jamesonite, 

 Jordanite, Leadhillite, Manganocalcite, Miargyrite, Ompha- 

 cite, Pyromorphite, Riebeckite, Sartorite, Stephanite, Stib- 

 nite, Topaz, Wulfenite, Xenotime, and others. 



Crystals in some ancient lead slags from the Mendips, 

 collected by Mr. Spencer during his vacation, have been 

 examined and determined. 



A chemical investigation has been made of various titano- 

 niobates of the rare earths, recently discovered in Swaziland. 



Quantitative chemical analyses have been made of the 

 above-mentioned Stanniferous Argyrodite, and also of 

 Miargyrite from Bolivia, a Euxenite-like mineral from 

 Swaziland, a Fiedlerite-like mineral from Laurium in Greece, 

 Semseyite from Wolfsberg in the Harz, Limestone from 

 Campbell Island, Basalt from Franklin Island, and two 

 Basalts from Cockburn Island. Farther, 106 doubtful 

 minerals have been qualitatively analysed, and many specific 

 gravity determinations have been made. 



Petrographical examinations have been made of the rock- 

 specimens collected during the Antarctic Expedition (1839- 

 43) of Sir James Clark Ross, and also of tracliytic rocks from 

 Abyssinia, which contain the mineral Riebeckite. Various 

 sets of rocks from Swaziland and Madeira have also been 



