Chap. VI. ] 
CAI DERITE. 
185 
times of considerable thickness, are met with '. He refers to this mas- 
sive garnet as that which Piddington called calderite, and gives an 
analysis by Tween showing only traces of manganous oxide, but showing 
on the other hand a large percentage of hme. The analysis shows that 
the garnet analysed approaches sufficiently near to the theoretical com- 
position of andradite to be called by that name. The name calderite 
is therefore wrongly appHed to this garnet ; unfortunately this mis- 
take has been repeated in Dana's System of Mineralogy. I have been 
able to find in the collection of the Geological Survey of India one speci- 
men of calderite labelled 'A. S. B.'. This means that it formed part 
of the collection of the Asiatic Society of Bengal ; and it is presumably 
one of the specimens that were examined and described by Pidding- 
ton. The rock is composed almost entirely of garnet and in fact could 
be described as massive garnet. In the hand-specimen it is a dark 
resin-brown as looked at from a little distance. When examined closely, 
however, it is seen to be of a rich orange-brown wherever a crack renders 
a portion of it transparent. There is some red in the colour of this 
mineral, so that it looks very like some specimens of spandite in appear- 
ance. I tested it for manganese, and found that it reacts distinctly but 
not strongly for this element, so that ths Piddington's analysis was 
either made on a piece of different composition, or Mallet's supposition 
as to its inaccuracy is correct. In places the specimen contains 
a dark green pyroxene. It is obvious that it will need a careful 
analytical examination of this garnet before it can be considered 
proved that it is a manganese-iron-garnet conforming to the formula 
3MnO.Fe.03.3Si02. 
During 1906 a specimen was received in the Geological Survey 
Office of a rock from Sirsia, 5-| miles N.-E. of Kharagdiha, in the north- 
ern part of the Hazaribagh district, the sender being Mr. J. W. Eoilard. 
The rock seems to be similar to that mentioned by Mallet ^ as being 
found in the bed of the Patru nadi, N.-E. of Gulgo, in the north part 
of the same district. He describes it as a mixture of garnet and cocco- 
lite containing traces of galena and copper. He refers to the garnet 
when it occurs in the massive form as calderite. Mr. Boilard's speci- 
men consists essentially of a mixture of a rich brown garnet and a bright 
green pyroxene, with galena present in parts of the rock, sometimes in 
abundance and sometimes only sparingly. Under the microscope 
the garnet is seen to be brownish pink in colour and the pyroxene very 
1 Rec. Geol. Surv. Ind., VII, p. 34, (1874). 
