and their allied Compounds. 273 



Chrysolite Type: — Trimetric, Monoclinic?. 



Chrysolite, 3RO, SiO 3 ; tephroite, 3MnO, SiO 3 ; knebellite, 

 3(MnO, FeO), SiO 3 ; forsterite; humite(?); chondrodite, MgFl 

 + 7MgO, 2SiOW 4 i?; lievrite, 3(3RO, SiO 3 ) + 2Fe 2 3 , SiO 3 . 



Epidote Type : — Monoclinic. 



Orthite or allanite, 3RO, Si O 3 + R 2 O 3 , Si O 3 ; gadolinite, 

 3(YO, RO), SiO 3 ; warwickite; enceladite ; epidote, 3RO, Si 3 

 + 2(R 2 3 , SiO 3 ); sphene, 3CaO, 3Ti O 2 , 2Si0 3 ; wichtyne, 

 chloritoid, chlorite spar. (See the present volume of the Philo- 

 sophical Magazine, Art. XXI.) 



Axinite Type : — Triclinic. 



Axinite, 3RO, 2 (SiO 3 BO 3 ) + 2R 2 3 (Si0 3 BO 3 ) ; danburite, 

 RO,B0 3 + 4ROSi0 3 . 



Tourmaline Type : — Hexagonal. 

 Tourmaline. 



Augite Type : — Monoclinic. 



Augite, 3RO, 2Si0 3 ; wollastonite, 3CaO, 2Si0 3 ; rhodonite, 

 3MnO, 2Si0 3 ; crednerite, 3(CuO, CaO),2Mn 2 3 ; spodumene; 

 acmite, NaO, Si O 3 + Fe 2 O 3 , 2Si 3 ; hornblende, RO, SiO 3 

 + 3RO, 2Si0 3 ; babingtonite, 3ROSi0 3 + 3RO, 2Si0 3 ; glau- 

 cophane (?), 3(3RO, 2Si0 3 ) +2(A1 2 3 , 2SiO s ). 



Spodumene is placed under this type on the authority of Hart- 

 well and Dana*. In respect to crednerite, see the present volume 

 of the Philosophical Magazine, Art. XXI. Glaucophane should 

 perhaps be placed near iolite. 



Muscovite Type : — Monoclinic. 



Muscovite (potash mica), 3RO, 12AP0 3 , 16Si0 3 ; margaro- 

 dite, RO, H 2 0, 2R 2 3 , 3Si0 3 ; margarite, 3RO, 12A1 2 3 , 8Si0 3 ; 

 lepidolite; emerylite; euphyllite. 



This type is by no means a satisfactory one ; but so little is 

 known respecting the true nature of the micas, that it seems 

 advisable at present to keep them distinct from other minerals. 

 Muscovite was so named by Dana. 



Phlogopite Type : — Trimetric. 

 Phlogopite (magnesia mica), 9RO, 2A1 2 3 , 5Si0 3 ; rubellane 

 (a variety of phlogopite?). 



* See the third edition of Dana's very able Treatise on Mineralogy, 

 p. 693. I should confeas, however, that the cleavage form of spodumene 

 seems to me to he triclinic. 



l'lul. Mag. S. 4. Vol. 3. No. 18. April 1852. T 



