138 EEPOET— 1891. 



Sections. — Clear ground-mass of allotriomorphic uepheline, 

 rather scantily mixed with microlites of sanidine ; but these 

 occur in places closely aggregated in small streamlike patches 

 with fluidal structure. Tufts and denser aggregates of pale- 

 greenish microlites ( segirine ? ) very abundantly and evenly 

 distributed tliroughout the clear ground-mass. Idiomorphic 

 nephelines very scarce. Larger sanidines, partly in Carlsbad 

 twins, also scantily distributed. Augite in columnar crystals 

 of green colour tolerably frequent, and mostly impregnated 

 with grains and dust of iron-ore ; some crystals are rendered 

 quite black-opaque by this ore. In the ground-mass the latter 

 is, however, very scarce. Apatite also scarce. 



4. Small Bidge hehincl Main Peak of Mount Cargill. 



Bock. — Quite similar in aspect to 3, but more strongly 

 porphyritic. 



Sections (a). — Clear ground-mass of allotriomorphic nephe- 

 line, densely filled with microlites of sanidine and greenish ones 

 of a3girine (?), all arranged in fluidal structure. Eather large 

 idiomorphic nephelines abundant, much cracked, and often 

 aggregated in groups. Large sanidines scarce. Green 

 columnar augite and brown columnar hornblende sparingly 

 distributed, the former predominating ; both much impreg- 

 nated with grains and dust of iron-ore, which are also abundant 

 in the clear base, and render the greenish microlites in parts 

 quite black-opaque. 



Sections {b). — These show the same ground-mass as (a); 

 but, besides the greenish microlites, occur others of larger size, 

 which are dark-brown, though mostly rendered black-opaque 

 by dusty iron-ore. They are long-acicular, and cross each 

 other in all directions, whereby an irregular dark network is 

 produced. It is probable they are acmite. The augites are 

 large, and mostly of light-brown and purple colour, green ones 

 being rare ; and the brown hornblendes are sometimes very thin 

 and long-columnar. Idiomorphic nephelines same as in [a) ; 

 but there occur more large sanidines, single and in Carlsbad 

 twins. Occasionally observable are large lath-shaped crystals 

 of plagioclase, grains of olivine, and particles of water-clear 

 glass, of irregularly-polygonal shape. 



5. Top of Middle Peak, Mount Cargill. 



Bock. — Greenish-black, dense, and slightly porphyritic. 

 Gives a large amount of gelatinous silica on treatment with 

 HCl. 



Sections. — Ground - mass of allotriomorphic nepheline, 

 densely filled with lath-shaped microlites of sanidine and 

 pale-green ones of aegirine ('?), all arranged in fluidal struc- 



