Antarctic Minerals. 207 



ANTARCTIC MINEBAI 8. 



Dr. R. D. Thomson exhibited specimens of minerals presented to him 

 bj Dr. Joseph Hooker, which he had collected at the Falkland Islands, 

 Kerguelen's Land, New Zealand, and other places visited by Captain 

 Ross' expedition. Captain Sibbald, late of H.M.S. Erebus, one of 

 the vessels engaged in the expedition, was present, and assisted Dr. 

 Thomson in pointing out the course of the voyage on a chart, and the 

 points from which the specimens were derived. 



The following are the analyses of some of the specimens:— 



OBSIDIAN. 



This specimen was from Ascension, and was analysed by Mr. James 

 Murdoch, in the College laboratory. 



Silica, 7097 



Alumina, .... 6*77 



Peroxide of iron, . . . .6-24 



Lime, .... 284 



Magnesia, . . . .1-77 



Soda and potash, . . . 11*41 



100- 



This analysis closely approximates to the result obtained by Berthier, 

 from a specimen procured from Pasco in Columbia,* but differs con- 

 siderably from the composition of obsidians from Iceland and Mexico, 

 which contain 10 per cent, more silica. 



Mr. James Murdoch also analysed a zeolite, from Kerguelen's Land, 

 which proved to be a white stilbite. The geological conformation of 

 this island appears to be volcanic, both from this circumstance, and 

 from a specimen of porphyry or volcanic slate, among the collection, 

 which was also exhibited. 



NEW ZEALAND OCHRE. 



This substance, which is a fine yellow pulverulent ochre, is described 

 by Dr. Dieflfenbach t as occuring near Mount Egmont, many hundred 

 feet above the sea in the bed of a stream ; and as being used by the 

 natives to paint their bodies in time of war, their houses and canoes. 

 It was analysed by Mr. George Aitken in the College laboratory, and 

 its composition found to be as follows by two analyses : — 



* Thomson's Mineralogy, I. 394. f Travels in N. Zealand. 



