Chap. XII.] 
KODURITE SERIES : NOMENCLATURE. 
249 
Owing to the long continued chemical changes by which tho manga- 
nese-ores have been produced from manganese silicates, the masses of the 
kodurite rocks as seen in mine workings are usually found to be 
extremely altered. In fact it is practically impossible to find perfectly 
fresh examples of any of the rocks of this series ^except, perhaps, at 
the non-tv^pical localities, Taduru and Chintelavalsa;. Hence, one 
usually has to judge of the original composition of the kodurite rocks 
by carefully noting how in one place one mineral constituent has been 
decomposed, and in another place another constituent ; and as the 
result of examining a large number of the many exposures to be found 
in the various workings, especially at Kodur, Garbham, and Rama- 
bhadrapuram, it has been found comparatively easy to arrive in this 
manner at the original mineralogical composition of the rocks of this 
series. 
The typical rock of the series is one composed of potash-felspar, 
manganese-garnet fspandite), and apatite, with or 
Nomenclature of the -vrithout pyioxene. This rock mav be called AWuri'^e 
kodiirite series. , ' • i , i' 7 i •. 
when pyroxene is absent and pyroxene- kodurite 
when this mineral is present. When quartz is present the rocks can be 
distinguished as quartz-kodurite and quartz- pijroxene-kodurite respectively. 
A biotite-kodurite has been found at Ramabhadrapuram, this and a mica- 
bearing manganmagiietite-spandite-rock from Garbham being the only 
mica-bearing examples of this series yet noticed^. The manganese- 
garnet may be regarded as the characteristic mineral of this series. 
To obviate the constant use of the cumbrous term manganese-garnet and 
to express the fact that this garnet, though probably very variable in 
composition, is intermediate between the manganese-alumina garnet, 
spessartite, and the lime-iron garnet, andradite, the term spandite has 
been coined (see page 163). Hence those roclcs that are practically 
free from felspar may be called spandite-rock, apatite-spandite-rock, pyro- 
xene-spandite-rock, etc., according to their composition. Those rocks 
composed mostly of pyroxene may be called manganese-pyroxenites ; 
whilst those varieties that are free from spandite and pjToxene may 
be called felspar-rock, and quartz-felspar-rock, etc. There is also an 
apatite-matujanmagnettte-spandite-rock contsiinmg & little mica; but it is 
uncertain if the manganmagnetite be an original constituent or not. 
Although very little analytical work has yet been done on the rocks of 
the kodurite series, yet, on the basis of their mineralogical composition, 
1 The complex rock found at Chintelavalsa (.^ee page 1114) also contains mica- 
II B 
I 
