254 



C. A. SUSSMILCH. 



sions of this mineral are abundant in the few pyroxene 

 crystals. 





Chemical Composition. 



Si0 2 



Per cent. 



69-82 



Per cent. 



SO 3 ... ... absent 



Al 2 O s 



12-41 



01 ... ... trace 



Fe 2 3 



110 



S(FeSr) ... absent 



FeO 



0-54 



Cr 2 O x ... absent 



MgO 



0-29 



NiO and CoO absent 



CaO 



1-86 



MnO 0-03 



Na 2 



4-63 



BaO 0-02 



K 2 



1-67 



SrO ... ... trace 



H 2 (100° C.) 



1-05 



Li0 2 ... ... absent 



H 2 (100°C.)+ 6-55 



V 2 5 ... ... absent 



CO 



0-03 





Zr0 2 



0-25 



Total ... 100-30 



P 2 5 



JVorm. 



0-05 





Specific gravity 2-266 



Quartz 



32-46 



Classification. 



Orthoclase . . . 



10-01 



Class I. Persalane 



Albite 



38-77 



Order 4 Britannare 



Anorthite 



8-34 



Rang 2 Toxanase 



Diopside 



0-65 



Sub-rang 4 Lassenose 



Hypersthene... 



0-40 



Magmatic name Lassenose, 



Magnetite 



0-93 





Ilmenite 



0-46 





Hematite 



0-48 





The specimen taken for analysis was the glassy variety 

 as this appeared to be the freshest. It will be seen that 

 nearly 90% of this rock consists of quartz and felspar 

 molecules, and that of the latter the albite molecules largely 

 predominate. For a field name quartz keratophyre would 

 appear to be that most suitable. 



No. 2 Flow. — This rock in the hand specimen is typically 

 ,pink in colour, is aphanitic, and usually markedly porphy- 



