808 
MANGANESE DEPOSITS IN INDIA : DESCRIPTIVE. 
[ Part IV : 
is possible that the difference is due to the cleavage corresponding with 
the banding or original bedding in the former case, and to the cleavag^ 
cutting the banding obliquely in the latter case. The accompanyin 
figure shows an actually observed case. In either case the rock is 
probably best described as a micaceous hematite-schist, or, when 
banded with siUca, as a banded micaceous hematite-jasper or quartzite 
or more simply as banded hematite-jasper or quartzite. 
micace ms hematite, 
pale lavender jaspcry quarlzite. 
micacoous h ematite. 
Fig. 18. — Bauded heruatitc jaiper i^howing slaty cleavage. Natural size. 
In several places these hematites have been greatly altered at the 
surface with the production primarily of 
Manganiferous hematite. i • i <• -i 
mangamierous hematite and later of p?ilo- 
melane. Quite fresh micaceous hematite has a bright red streak, 
but as it becomes more and more manganiferous the streak changes 
through dull red, chocolate, brown, and brownish-black, to the black 
colour characteristic of psUomelane. This change is also accompanied 
by a gradual loss of lustre (and of hardness, in the case of the harder 
variety of hematite) and texture, with the production of a dull black 
soft rock still retaining the abundant signs of the original schistosity. 
In the later stages of the change thin veins of psilomelane appear both 
parallel to and cutting across the lamination of the hematite, and as 
irregular segregations ; but at the earlier stages it is not possible to see 
what is causing the change of character. It may possibly be a replace- 
ment or coating, scale by scale, of the original hematite by psilomelane, 
so that the hematite individuals still remain separate; whilst later they 
unite to form visible psilomelane in places. Such ore, in which traces 
of the original structure stUl remain, and in which visible psilomelane 
may or may not have appeared in any quantity, is what has been 
described as manganiferous hematite. 
