REPORT OF TEE CHIEF ASTRONOMER 415 



SESSIONAL PAPER No. 25a 



Analysis of ' shacJccmite ' — Continued. 



Mol. 



HoO at 110°C -80 



H.0 above 110°C 4-63 -258 



P 2 5 -59 -004 



CO, -35 



.99-89 

 Sp.gr 2-528 



A second, non-vesictdar specimen with more abundant augite had a specific 

 gravity of 2-637. 



Two different norms were calculated. For the one the combined water was, 

 as usual, neglected and all the soda was referred to albite and nephelite mole- 

 cules. The result is : — 



Orthoclase 14-46 



Albite 43-49 



Anorthite 16-96 



Nephelite 5-40 



Hypersthene 3-50 



Diopside ,. .. 2-37 



Hematite 3-36 



Magnetite 1-39 



Ilmenite 1-37 



Apatite 1-24 



Water and CO, 5-78 



99-32 



A second norm was calculated on the assumption that the combined water- 

 should not be neglected; in this case analcite is a standard mineral, taking the 

 place of nephelite as the lenad. This norm is essentially like the first except 

 that the albite is here 33-54 and the analcite replacing the nephelite is 16-72. 



According to the first calculation this rock enters the dosodic subrang, 

 akerose, of the domalkalic rang, monzonase, in the dosalane order, germanare — 

 as defined in the Norm classification. 



According to the second calculation the rock enters the dosodic subrang, 

 essexose, of the domalkalic rang, essexase, in the dosalane order, norgare. 



In the older classification the rock may be called an analcitic rhomb-por- 

 phyry; if any systematist wishes a more compact, single- word name for this 

 new petrographic type, he could refer to it as ' shackanite.' This word is coined 

 from the name of the railway station (Shackan) at the southern foot of the 

 ridge which is crowned by the analcitic rock. Such naming would have the 

 advantage of avoiding the use of ' porphyry ' as a systematic designation for 

 another species of effusive lava. The writer would prefer to see the term 'porph- 

 yry' restricted, in technical petrography, to the porphyritic intrusive rocks. 



Other Occurrences. — The analcitic rhomb-porphyry lava, generally vesicular, 

 also crops out liberally on the strong ridges north and northwest of the Kettle 

 River bridge, six miles above Midway. The upper part of each ridge, through 



