144 
MANOANJ SF DFPOSTTS OF INDIA : MmERALOGV. [ PaP.T I : 
these all being dark brown in colour. The opaque portion, moreover, 
seems to be black and brown in patches, the brown perhaps indicating 
that the fresh rhodonite contains a considerable proportion of iron oxides. 
In some cases the final result seems to be psilomelane, in others braunite, 
the intermediate product being an indefinite dark brownish black ore 
that can be scratched mth comparative ease. It seems probable that 
the latter variety would not pass into compact braunite without the in- 
troduction of manganese in solution from other portions of the mass of 
rock in which the altering mineral occurs. The consequence of the ease 
with which this mineral undergoes oxy- alteration is that all outcrops of 
rhodonite-bearing rocks are black (or dark bro\^Ti) ; but when the rock is 
broken open it is frequently found that this blackening does not extend 
for more than 1 to 2 inches in depth, the bright pink mineral lying 
beneath. Nearly all the loose blocks first found by Mr. Middlemiss near 
Chintelavalsa and Taduru in the Vizagapatam district, are completely 
blackened outside and are quite fresh inside, the blackened coat being 
often as much as 2 inches thick. This proves that the blackening of the 
mineral is going on at the present day ; for these blocks must have been 
blackened, at least on most sides, since they were detached from their 
original position in situ, which lies on the hill-side above, and from 
which such blocks are presumably still being detached under the 
influence of the ordinary meteoric agencies. 
In my paper ' Manganese in India ' ^ I have already drawn 
attention to the fact that rhodonite-rock in other 
mental stone' parts of the world is frequently turned to account 
as an ornamental stone on account of its great 
beauty when polished, the most famous locality for this industry 
being the Ural Mountains. In some of the deposits of the Central 
Provinces there are considerable amounts of beautiful examples 
of both rhodonite-rock, and of rose-pink rhodonite-rock studded with 
orange.coloiired spe-sartite crystals. As localities for the former 
Manegaon and Risara in the Nagpur district may be mentioned, 
whilst fine examples of the second variety are to be found at Chargaon 
in the same district. 
I have, since that paper was written, been able to re-visit and examme 
the Manegaon deposit. It had been much more opened up than at the 
time of my first visit ; and I must confess my disappointment at the small 
quantity of good rhodonite-rock suitable for use as an ornamental stone 
that seems to be available, this being due, not to any deficit in the quan- 
1 Trams. Min. Oeol. Inat. Jnd., I, p. 120, (1906). 
