600 
maxga>t:se deposits of ixdia : economics. [PabtIII: 
When it is remembered that even if the ore contained 95% Mn02, which 
is equivalent to 60% of manganese, and were sold for its manganese at 
16 pence per unit, it would fetch only £4 a ton, i.e., less than ore con- 
taining only 70% of MnOg eqmvalent to only 44% manganese, if sold 
for its MnOo, it will be seen that the extra cost of bagging the ore 
would be handsomely repaid ; and corsideriug the great increase in the 
price for the higher grades, it would probably pay to concentrate the ore 
before shipping. 
Another use to which manganese-ore is put on accoimt of its oxidizing 
power is the decolourization of glass i, from 
U.-;e of manganese for the i.- i -j. „ i j ^ 
deoolourization of glass. ^^^^^ \^ removes the green colour due to 
ferrous iron. P}Tolusite for this purpose must 
be extremely pure — iron being of course a very deleterious con- 
stituent — and fetches a very high price. The only pyrolusite sufficiently 
pure for this purpose, yet found in any quantity in India, is that 
of Pali in the Xagpur district. A picked specimen of this (see 
No. 9.32 on page 82) yielded on analysis 95-57% Mn02 with only 
0-06% Fe903. Of ore similar to this, a sufficient quantity could probably 
be won to pay handsomely for the trouble of extracting it from the 
limestone in which it occurs in scattered pockets. A bulk sample of 
ore not specially selected for this purpose gave 72 -71^0 Mn02, ^vith still 
only 2-98% FcsOg. 
A well-known region from wliich high-grade pyrolusite has long been ' 
obtained suitable for use for chemical purposes and for the glass industry 
is Nova Scotia and New Brunswick. Some of the ores from this region 
are exceptionally high in Mn09 and low in iron. The less pure ores are 
often prepared for the market by crushing, washing, and sizing with 
screens. 
To give an idea of the high prices that the Canadian ores fetch I give 
below a table showing the official statistics for the quantity and value of 
the Canadian production of manganese-ore from the years 189.3 to 1905 ; 
the values per ton for each year are shown in the last column. It 
will be seen from this that the value of the Canadian ores has fluctuated 
during this period from a maximum of £19-12-3 per ton in 1893 to a 
minimum of f2-5-7i in 1901, the value for the last year for which I have 
1 According to Knowledge and Scitntific Netfs, October 1907. p. 230, the use of 
manganese oside as a decolourizer of glass was known to the Romans, colourless glass be- 
coming popular about the first century A.D. A specimen of colourless glass, unearthed 
at Raalburg, near Hamburg, and of Roman origin, showed 0-36% of manganese oxide and 
0-49% of iron oxide. 
