106 MANGANESE DEPOSITS OF INDIA : MINERALOGY. [ PaBT I : 
manganates. An ore described by E.G. Williamsl from Soledad in 
Panama in Central America, as massive and like psilomelane, was 
analysed by W. E. Ford in Prof. Penfield's laboratory. Penfield says 
the ore agrees well with the composition Mn0.2Mn02 or Mn305, and 
may be a new mineral species. A conversion of the analysis given 
into manganates shows that it agrees very well with the formula 
R'''2Mn05, the oxygen error being a deficit of 0"o4%. 
I wiU now give a brief description of the spedmeiis of which the analyses 
are given on page 98. Each specimen was broken 
Description of jj^^^ piece used for analysis and the other 
specimens. p 
kept for reference. 
1157. — Guguldoho. 
This piece was a portion of the hepatiform concretion mentioned on 
page 99. I did not find it in situ, but obtained it from a stack of quar- 
ried ore. The piece selected for analysis was broken from a concentric 
shell about | inch in thickness. It shows a finely concentric structure 
parallel to the exterior of the shell, the bands being so fine as to impart 
to the specimen a somewhat satiny lustre. In grain it is extremely fine 
and in colour a rather light steel- grey, with a bluish tint in the sun. The 
colour of its streak is brownish black. Its hardness is just over 6, and 
the specific gravity of the piece analysed 4"26, the closeness of the 
texture of the specimen being well exemplified by the fact that it did 
not exhibit any noticeable porosity when left to soak in water. The 
outer and inner coats of the specimen were covered with a thin 
brownish skin exhibiting a few minute micaceous scales, but this skin was 
completely removed before the specific gravity was taken. The fracture 
is beautifully conchoidal. 
A. 372. — Avagudem. 
This specimen was faelected from the stacks of ore at this mine. This 
type of ore is rather cavernous and contains both ferruginous patches 
and soft black patches. After a little trouble, however, some 6 granmies 
of the mineral free from these blemishes were obtained ready for analysis. 
This variety has the appearance of shghtly tarnished metallic lead, its 
colour being just a little darker, but its lustre very similar. It appears 
absolutely homogeneous, and has a brownish black streak. The fracture 
> Trans. Amer. Inat. Min. En ., XXXIH, pp. 203, 204, (1902). 
