PHYSIOGRAPHY. 



Diallogite. 



1. The varieties of the present species have often been confounded 

 wtth other minerals, one of which has been proposed by BREITHAUPT 

 A* a distinct species, an account of which will be given at the close of 

 (his description. 



Before the blow-pipe, its color is changed into grey, brown and black, 

 and it decrepitates strongly ; but is infusible without addition. It is ea- 

 sily fusible in glass of borax, which thereby becomes of a violet blue 

 color. If exposed to the air, its natural color is changed into brown. 

 Many bright rose-red varieties become paler on being exposed in a sim- 

 ilar manner. It effervesces briskly in nitric acid. 

 2. Analysis. 



By DuMENiL. By BERTHIIR, 



fr. Nagyag. 



Oxide of manganese - 54-60 '- - 56-00 



Carbonic acid - 33-75 - - 38-60 



Oxide of iron 1'87 -, - 0-00 



Silica 4-37 - - 0-00 



Lime 2-50 - 5-40 



S. It occurs for the most part in metalliferous veins, with various ores 

 of Iron and Copper, and with Quartz. It is also found in beds with oth- 

 er minerals containing manganese. 



4. It is found in several of the Saxon mines, particularly in the neigh- 

 borhood of Freiberg ; also at Nagyag and Kapnik in Transylvania, near 

 Elbingerode in the Hartz, and in other countries. 



i. Manganeseous Carbon- Spar. BREITHAUPT, 



Pon P = 107 30'. 



Cleavage parallel to the primary, easily effected. 

 Hardness (scale of BREITHAUPT) = 5-75 . . . 6-0. Sp. gr. 

 3-592. 



BREITHAUPT includes in this species the mineral from Kapnik only, 

 .This variety was analyzed by BERTHIER, and found to contain, 

 Carbonic acid .... 30-4 



Protoxide of manganese ... 41-0 

 Lime 43 



Quartz ... - 21 



96-7 



