Prof. A. E. Nor denskibld— Geology of Spitzhergen. 123 



becomes dark brown throngh the action of the atmosphere. Under 

 the microscope olivine (Tornebohm) and chlorite may be discovered 

 as occasional ingredients. The latter mineral, however, is believed 

 to be absent in the rock from a number of the localities, whereby it 

 takes the nature of dolerite. 



The Spitzhergen diabase has been analyzed : (1) from the Goose 

 Islands in Ice Sound by Mr. G. Lindstrom (paper previously quoted, 

 page 671) ; (2) from Tschermaksberg by Professor Teclu (Min. 

 Mitheilungen, 1874, h. iv. p. 263) ; (3) from Saurian Hook by Teclu 

 (paper quoted, p. 264).^ 



The specific gravity of 2 and 3 is ^ 2-98. 



01-17 ... 50-96 



trace ... trace 



10-72 ... 10-11 



0-77 ... 5-39 



14-29 ... 5-23 



17-87 ... 27-78 



Sili-ca 



1. 



. 49-78 



Titanic acid 



. 2-97 



Lime .. 



. 9-44 



Magnesia 



. 5-65 



Alumina 



. 14-05 



Oxide of iron 



. 14-86 



Protoxide of manganese .. 



•13 



Potash \ 



Soda } 



,. 1-70 



Loss 



. 1-42 



[l 



0-18 ... 0-27 



96 ... 004 



•90 ... -99 



100-00 100-86 100-77 



This rock commonly occurs in strata which, with the same regularity 

 as the sedimentary rocks and without branching out into side veins, 

 form distinct links in the Mountain Limestone, the Triassic and 

 Jurassic formations. Less frequently it occurs in isolated mountains, 

 seldom in the form of veins. In numberless cases it occupies the 

 slopes at the foot of the mountain where the black stone surfaces 

 are like a parquet floor divided into chequers, corresponding to the 

 sections of the pillars, into which the stratum is cleft, and at the 

 same place the summit of the mountain is generally occupied by a 

 horizontal, black or rust-brown diabase stratum, also cleft into basaltic 

 pillars. As there are no cavities, the minerals with which these are 

 commonly filled are also completely absent.^ 



With respect to the occurrence of the prismatic structure in basalt, 

 I may be permitted to refer to my sketch of the Geology of Spitz- 

 hergen, p. 35, where it is stated that " No satisfactory explanation has 

 hitherto been given of this remarkable phenomenon, which is 



^ In quoting these analyses von Drasche gives utterance to a doubt of the correct- 

 ness of Lindstrom's determination of titanic acid in the addendum: " Wie leicht 

 kann ein dui-ch Fluss-saure noch nicht, ganz aufgeschlossener Theil des Silikates als 

 Titansaure gewogen warden." This doubt is unwarranted, and perhaps shows why 

 Teclu only found a trace of titanic acid. Small quantities of titanic acid _ are not 

 obtained in the way stated by Herr von Drasche, because the acid passes into the 

 solution. In the analysis made by Lindstrom at the laboratory for mineral analysis 

 at the Eiks Museum, the titanic acid was precipitated by boiling and the pecipitated 

 acid was forced from iron by means of acetic acid and hydi-osulphate of ammonia. 



2 Among the pebbles on the north-east side of JSTorth-East Land I found sorae 

 pieces of Chalcedony, wbose form clearly showed that they had been formed in 

 cavities of basalt. This is considered to prove that such rocks occur on the groups 

 of islands north-east of Spitzbergen. Perhaps it was in these regions that the 

 eruptions took place from which the Spitzbergen diabase beds originated. According 

 to Keilhau, pebbles with cavities also occur on Stansforeland. 



