62 Canadian Record of Science. 



nepheline syenite pegmatites of the boundary zone along 

 the Langesundfjord, corresponding to the nepheline syenite 

 rocks of the neighborhood, and quite uninfluenced by the 

 fact of whether they occur in rocks poor or rich in nephe- 

 line, i. e. whether they occur in laurvikite or in nepheline 

 syenite; the akmite granite pegmatite of Rundemyr, Eker, 

 in Silurian limestones and slates, corresponding to the ad- 

 jacent aegerine granite of Kyrfjeld, etc.; the granite peg- 

 matites of Hittero in labradorite rock and norite, corres- 

 ponding to the granitite of the neighboring main-land, etc. 

 From the occurrence of certain mineral species, such as 

 albite, some authorities have wished to deduce certain con- 

 clusions with regard to the origin of pegmatite veins in 

 general. 1 Although at the present time it ought to be 

 superfluous to reply to such propositions made many years 

 ago, similar views are still put forward from time to time 

 and render a reference to them necessary. Among the 

 first to describe the microperthitic intergrowth of orthoclase 

 and albite, or microcline and albite, from the above-men- 

 tioned locality, was Credner, and he quite correctly con- 

 sidered it to be a primary intergrowth ; as far as this phe- 

 nomenon is concerned, it also occurs very plentifully in the 

 syenite and nepheline syenite veins which have been dis- 

 cussed in this treatise (" Die Mineralien der Syenitpegma- 

 titgiinge"); it occurs, however, developed in an exactly 

 corresponding manner, very commonly, indeed predomin- 

 atingly, in the normal-grained trachytoidal foyai'tes of Lau- 

 genthal which are true eruptive veins, and even in the 

 same combination, microcline-albite, as in the pegmatite 

 veins of the Langesundfjord, etc. Albite also occurs inde- 

 pendently in the same rocks, though not widely distributed, 

 in the form of individual crystals developed tabularly 

 parallel to the brachypinacoid. In view of these facts, all 



1 See H. Credner, 1. c. p. 179 : " Albite forms for the association of minerals of 

 which it is a member a 'guide' for aqueous formation. Now as albite is most 

 intimately intergrown with the principal component of our pegmitite and granite 

 veins, with orthoclase, — as the one, so the other of these two feldspars must have 

 originated, and also the quartz which penetrates them both in the graphic 

 granite structure ;" see also F t Klockmann, L c. p. 406. 



