6 1 2 HENR V S. IV A SHING TON 



Megascopically, this is similar to the other, but is darker gray 

 and somewhat finer grained. 



In thin section it shows fewer phenocrysts of diopside and 

 olivine than the other, but more abundant, well-formed, horn- 

 blendes, which have all been altered, in some cases entirely,, 

 in others only partially, leaving some unchanged hornblende 

 substance in the center. This alternation has not been as 

 thorough as in the preceding, and, while here and there altera- 

 tion to the usual diopside-magnetite aggregate is seen, in most 

 cases the spaces formerly occupied by hornblende show a mass 

 of the brown, pleochroic orthorhombic rods, which I have iden- 

 tified with hypersthene. 



The groundmass is similar to the other, but flow structure is 

 well marked. There are similar plagioclase laths (here ande- 

 sine), also olivine and diopside crystals, generally stouter and 

 better crystallized, and smaller grains of magnetite but scarcely 

 any apatite. The most important difference is the presence in 

 abundance of small round areas of a clear, colorless mineral, of 

 low refractive index, and generally isotropic, containing inclu- 

 sions of diopside needles and magnetite grains, arranged either 

 centrally or zonally. While these round spots are mostly too small 

 to show very marked abnormal double refraction, yet they occa- 

 sionally do so, and there seems to be no doubt that they are to 

 be referred to leucite. The mesostasis here is colorless and 

 almost isotropic and glass-like, but it stains by treatment with 

 HC1 and fuchsine. 



In the table are given the two analyses recently made by 

 myself, as well as the corresponding ones of Rohrig. A few 

 other analyses of similar rocks are inserted for comparison, and 

 will be referred to subsequently. 



It will be seen that Rohrig's analysis of the normal kulaite 

 (II) agrees very well with mine (I) in all respects except in 

 Fe 2 O s and K 3 0, which are respectively about 2 per cent, 

 higher and lower. On the other hand, his of the leucite-kulaite 

 (IV) resembles mine (III) only in MgO, CaO, and A1 3 3 , the 

 Ti0 3 present being weighed by him with the A1 2 3 . The other 

 constituents differ rather widely. 



