MANGANESE. 191 



Triplite. 



Trimetric. Usually massive, with cleavage in three di- 

 rections. Color blacidsh brown. Streak yellowish gray. 

 Lustre resinous; nearly or quite opaque. ti.=5-5-5. G.= 

 3-4-3 8. 



Composition. (Mn,Fe) 3 8 P 2 + RF 2 , affording about 30 

 per cent, of manganese protoxide, 8 of fluorine. Fuses 

 easily to a black magnetic globule. B.B. imparts a violet 

 color to the hot borax bead. Dissolves in hydrochloric 

 acid. 



Obs. From Limoges in France. Bather abundant at 

 Washington, Conn., and sparingly found at Sterling, Mass. 



Heterosite, Alluaudite, Pseudotriplite, are regarded as results of 

 alteration, either of triphyline or of triplite. 



Triploidite. A manganese-iron phosphate like triplite, but having 

 the fluorine replaced by the elements of water. From Redding, Conn. 



Dickinsonite. An oil-green to olive-green manganese-iron-calcium 

 phosphate. From Redding, Conn. 



Reddingite. A rose-pink hydrous manganese-iron phosphate. Mn 3 

 O b P 2 + 3aq, isomorphous with scorodite and strengite. Redding, Ct. 



Fairfieldite, hydrous manganese-calcium phosphate. Ibid. 



Hureaulite. Rose-colored to brownish-orange hydrous manganese- 

 iron phosphate. From Hureaux, France. 



Rhodochrosite. — Manganese Carbonate. 



Rhombohedral. R A R = 166° 51'; like calcite in hav- 

 ing three easy cleavages, and in lustre. Color rose-red. 

 H. =3-5-4-5. G. = 3 4-3-7. 



Composition. Mn 3 C = Carbonic acid 38 6, manganese 

 protoxide 61-4=100. Part of the manganese often replaced 

 by calcium, magnesium or iron. 



Obs. From Saxony, Transylvania, the Hartz, Ireland ; 

 Mine Hill, New Jersey ; Redding, Conn.; Austin, Nevada; 

 Placentia Bay, Newfoundland. 



Rhodonite. A manganese silicate. See p. 247 



General Remarks. Manganese is never used in the arts in the pure 

 state ; but as an oxide it is largely employed in bleaching. The im- 

 portance of the ore for this purpose depends on the oxygen it con- 

 tains, and the facility with which this gas is given up. As the ores 

 are often impure, it is important to ascertain their value in this re- 

 spect. This is most readily done by heating gently the pulverized ore 

 with hydrochloric acid, and ascertaining the amount of chlorine given 

 off. The chlorine may be made to pass into milk of lime, to form a 

 chloride, and the value of the chloride then tested according to the 

 usual modes. The amount of chlorine derived from a given quantity 



