SYNOPSIS OP PART 1. 
Ixvii 
exhibiting polarity. H = 6'5. G = 4"74 to 4'85. Its composition seems 
to be best expressed by the formula 3Mn30i.2Fe203. It has been 
found at Beldongri, Nagpur district, Central Provinces ; and Garividi, 
Vizagapatam district, Madras. 
S ita par ite.— This is another dark bronze-grey mineral, easily distiji- 
guished from vredenburgite by the fact that it is only slightly magnetic. 
Its composition is complex and may be represented somewhat doubt- 
fully by the formula 9Mn2O3.iFe2O3.MnO2.3CaO. It is found at 
Sitapar, Chhindwara district, Central Provinces. 
Braunite. — Measurable ciystals of this mineral have been found at 
five localities in India, narcely, Kajlidongri in Central India, and 
Kacharwahi, Lohdongri, Kodegaon, and Sitapar, in the Central Pro- 
vinces. Ten figures of crystals are given illustrating the following 
10 forms , of which the last three are ones not previously recorded on 
this mineral :— (001), (100), (110), (101), (111), (421), (423), (42^), (201), 
and (865). The total number of forms that has been recognized on 
braunites from all parts of the world is 16. The mean value of the 
fundamental angle pp' is determined as 77° 21'. This being so 
close to the value 77^19' found by Flink for Swedish braunites, the 
latter, corresponding to a value of 0'99220 for the vertical axis c , is 
accepted as the mean value for braunite ; but it is probable that there 
is a real variation, between narrow limits, of the value of this angle 
owing to differences between the composition of different crystals. 
The composition of the mineral is discussed at some length, the previous 
literature on the subject being reviewed. The conclusion arrived at 
is that the formula of this mineral can be represented in the most 
general way as : — 
mRMn03 + HRSi03, 
in which R is to a large extent Mn, but may be partly Fe, Ca, Ba, etc.; 
and in which the ratio tn : n varies between 4 : 1 and 3:1. The three 
chief varieties correspond to the three formulae : — 
4Mn203 + MnSiOa 
7Mn203 + 2MnSi03 
3Mn203-f MnSiOg. 
The isomorphism of the different varieties of this mineral is explained 
