PHYSIOGRAPHY. 131 



Pyropbyllite. 



PYROPHYLLITE. 



1. Heated before the blow-pipe, it swells up, but is infusible. It 

 ields moisture by calcination ; the residue being heated with solution 

 of cobalt, asumes a blue color. 



2. Analysis. 



Silica . 59-79 



Alumina 29-46 



Magnesia 4-00 



Oxide of iron ....... 1'80 



Water 5'62 



Silver a trace. 



3. It is brought from the Ural mountains. 



PYROPHYSALITE. (See Topaz.) 



PYRORTHITE. 



Massive : composition columnar. Fracture conchoidal, splin- 

 tery, earthy. 



Lustre resinous. Color brownish-black ; if decayed, yellowish- 

 brown. Streak brownish-black. Opake. 



Hardness, is scratched by Calcareous Spar. Sp. gr. = 2-19. 

 1. If gently heated on one side, it takes fire, arid burns without either 

 flame or smoke ; after which, it becomes white, and melts into a black 

 enamel. It gives a transparent glass with borax ; and is soluble in heat- 

 ed acids, with the exception of a black powder. 



2. Analysis. 

 By BERZEL.IUS. 



Silica 1043 



Alumina 



Protoxide of cerium 13-92 



Protoxide of iron 6 ' 08 



Yttria 4 ' 87 



Lime 



181 



Protoxide of manganese 



Water 26-50 



Carbon . - ' - 31 ' 41 



