456 M. Berthier on Two Vaiietiesof [JuNr, 



Article XIV. 



Analysis oj Two Varieties of Native Carbonate of Manganese* 

 By M. Berthier. 



The existence of carbonate of manganese has been long since 

 stated by several chemists ; but as some mineralogists still enter- 

 tain doubts on the subject, I think it may be useful to pubHsh 

 the analyses which I have performed of two minerals that are 

 essentially composed of carbonate of manganese. One of them 

 is from ^Nagyac, and was sent to me by M. Cordier ; and the 

 other, from Freyberg, was brought by M. de Rivero. 



The carbonate of manganese from Nagyac accompanies the 

 ores of gold, tellurium, Sec. ; it is very much mixed with lamellar 

 quartz ; it is of a flesh-red colour, and transparent at the edges ; 

 its powder is white ; it becomes brown by calcination ; it dis- 

 solves in cold nitric acid, with the evolution of carbonic acid 

 gas. The solution gives a yellow precipitate with the hydrosul- 

 phurets, which shows that no iron is present ; it does not con- 

 tain the smallest trace of magnesia. 



A portion of this mineral was dissolved in nitric acid, 0*21 of 

 quartz remained unacted upon. The manganese was separated 

 from solution by an hydrosulphuret, and the lime was afterwards 

 precipitated by an oxalate, the calcined precipitate gave 0*043 

 ofhme. 



Another portion was treated with pure sulphuric acid, and the 

 residuum was well dried to expel the excess of acid ; this resi- 

 duum weighed 1-245; deducting 0'21 of quartz and 0'103 of 

 sulphate of lime which it must contain, there remain 0*932 of 

 of sulphate of manganese, equivalent to 0*443 of the protoxide 

 of this metal. According to these experiments, and determining 

 the quantity of carbonic acid by the deficiency, this mineral is 

 composed of 



Quartz 0*210 



Protoxide of manganese 0*443 



Lime 0043 



Carbonic acid 0*304 



1-000 

 Which, deducting the quartz, gives : 



Protoxide of manganese 0*560 



Lime 0*054 



Carbonic acid 0*386 



1-000 



* From the Annales des Mines. 



