TRANSACTIONS OF SECTION C. 139 



tare. Large idiomorphic nepheliues and sanidiues rather fre- 

 quent, the latter often in Carlsbad twins. Large columnar 

 augites of purple, light-brown, and green colour abundant ; 

 some with broad black margins of iron-ore, but the greater 

 number more or less densely filled with this ore. In the 

 ground - mass the latter is rather sparingly distributed. 

 Olivine is tolerably frequent in irregular grains and crystals, 

 each with margin of black, dusty iron-ore. Apatite scarce. 



6. Bange near Mount Cargill. 



Bock. — Dark greenish-grey, with small black spots ; close- 

 grained, and slightly porphyritic. Gives a tolerably large 

 amount of gelatinous silica on treatment with HCl. 



Sections. — The clear ground-mass consists of a mixture of 

 allotriom Orphic nepheline, microlites of sanidine, and also 

 of plagioclase, and is filled with pale-green microlites of segi- 

 rine ('?). Small idiomorphic nephelines numerous. Large 

 crystals of sanidine and plagioclase frequent, the former appa- 

 rently predominating. Columnar augites, often of large size, 

 of green and pale-brown colour, abundant, but most are more or 

 less densely tilled with grains and dust of black iron-ore. In 

 the ground-mass this ore is also abundant. Apatite scarce. 



7. Bange between Pine Hill and 3Iou)it Cargill. 



Bock. — Dark greenish-grey, dense, and slightly porphyritic. 



Sections. — Clear ground-mass of allotriomorphic nepheline, 

 densely filled with microlites of sanidine and pale-greenish 

 ones of ffigirine (?) ; all showing fluidal structure. The most 

 striking porphyritic inclusion in this is greenish-white olivine 

 in numerous irregular grains and perfect crystals, some of 

 unusual development, consisting in a long narrow colunniar 

 extension. One crystal, terminated at both ends by pyramidal 

 planes, measures l-75mm. in length and 0-25mm. in width : 

 i.e., it is seven times longer than broad. It has a strong black 

 margin of iron-ore, and is zoned inside parallel with the sides 

 by a brown ferruginous streak, while a line of brown iron- 

 spots surrounding small grains' of iron-ore runs lengthways 

 through the centre. All the other crystals and grains have 

 also broad rims of black iron-ore, and several are broken up 

 similarly to the grain shown in Fig. 4 (o). Augite is abundant 

 in large purple-brown, slightly pleocliroic crystals, all with 

 black margins, and more or less densely impregnated with dust 

 and grains of iron-ore, which is also plentifully distributed 

 throughout the base between the inclusions. Idiomorphic 

 nephelines scarce. No large sanidines ; no hornblende ; very 

 little apatite ; a few small particles of water-clear glass. 

 There are, however, a great number of long columnar or aci- 



