/krj 



Where the felspar has been strained and the lamellae bent, 

 thin lenticular concave-convex lamellae, twinned on the 

 albite law appear between the long bent lamellae. (See 

 fig. 3.) 



points of 



Alterations.— In his work on the gabbro rocks of Scotland 

 Judd 1 has described in detail the processes of alteration 

 which felspars may undergo under fairly deep seated con- 

 ditions, the processes being akin to schillerization, and 

 resulting in the production of chatoyant forms of felspar. 

 Effects precisely similar to those observed by Judd are 

 exhibited by the felspars of the Dundas rocks. In these 

 have been developed long cavities, negative crystals, lying 

 chiefly parallel to 010 but also in several other planes. 

 These are filled in with dark oxides, magnetite, ilmenite, 

 chromite or rutile. Lacroix* opposed Judd's view, and his 

 alternative hypothesis 



ntly received tiie supporl 



J. W. Judd, op. cit., pp. 375 an< 

 Bull. Min. Soc ¥ France, April, 



