On the Norian or " Upper Laurention " Formation. 187 



The inclusions are so minute that they cannot be isolated 

 and chemically examined. Their form is not defined with 

 sufficient sharpness and constancy to enable their crystallo- 

 graphic character to be determined. Some investi- 

 gators have endeavored to gain some notion of the nature 

 of these small bodies by observing their deportment when 

 treated with concentrated acids, but the results obtained 

 are contradictory. Judd (1. c.) found that they resist con- 

 centrated hydrochloric acid. Yogelsang (1. c.) treated a 

 small piece of feldspar from Paul's Island, Labrador, which 

 contained them, with hot hydrochloric acid for four days. 

 He found that the acid had strongly attacked the feldspar 

 but could perceive no alteration in the needles, except that 

 they had become slightly paler. Hagge l however found 

 that in the same rock from Labrador, all the brown scales 

 were dissolved when treated with the acid for a time too 

 short to effect a decomposition of the feldspar. He con- 

 sidered that they were probably gothite. 



They are evidently some iron compound, and the 

 peculiar color of the transparent individuals taken in con- 

 nection with the fact, that, as will be shown, under 

 certain conditions, they unite to form small masses of 

 titanic iron, leads to the belief that the view of Professor 

 Rosenbusch, is correct, namely that they consist princi- 

 pally of titanic iron ore or ilmenite. The transparent ores 

 have the form of the mineral known as micaceous titanic 

 iron ore, which Lattermann l found intergrown with 

 magnetite in the nephelinite of the Katzenbuckel. The 

 peculiar color of this mineral moreover resembles perfect- 

 ly that of these inclusions. The diverse results which the 

 several investigators have obtained in the matter of the solu- 

 bility of these inclusions may perhaps be explained by the 

 fact that the titaniferous iron ore in some hand-specimens 

 might be richer in titanic acid than in others. 



In this connection it must be mentioned that titanic iron 

 ore is a mineral which is constantly found in these anor- 



1 Hagge, Microskopiche Untersuchung uber Gabbro and verwandte Gesteine, 

 Kiel, 1871. S- 46. 



Lattermann in Rosenbuech Mass. Gest., p. 786. 



