J 34 MANGANESE DEPOSITS OF INDIA: MINERALOGY. [ ParT I : 
the percentage of manganese is rouglily the same in the two minerals, 
the best way of distinguishing between them would seem to be to test 
them for sodium. A marked reaction for this element might then be 
taken to show that the mineral was urbanite, whilst failure to obtain 
this reaction to any but small extent might be taken to indicate the min- 
eral to be schefferite. The above distinction would, however, only hold 
on the assumption that all the Indian yellow or brown manganese- 
pyroxenes must be either one or the other of the two minerals named 
above. This, of course, by no means follows ; so that although the Indian 
brown and yellow manganese -pyroxenes can be provisionally divided into 
these two species by means of the sodium test, it will need the complete 
chemical analysis of various picked specimens to definitely settle this 
question. The characters of these two minerals that are of importance 
in addition to the chemical composition are given below, and were 
extracted from Dana's System of Mineralogy. 
Schefferite : — Cleavage distinct, prismatic. Colom* yellowish brown 
to reddish brown. Optically + . Bx^^ c=zc v c 44° 25J^ Schefferite 
is foimd at the Langban manganese mine, Sweden. The variety known 
as iron-schefferite, on account of the large amount of FeO present 
replacing MgO and CaO, is black in colour when frjm Pajsberg, and 
then has c a c— 49^ to 59° for different zones ^n the same crystal. 
The variety from Langban is brown and has c c=:69°. 
Urbanite: — Cleavage, prismatic (m) distinct; (c) less so. H. = 5 
to 6. G.r=3'52 to 3'53, colour brownish black to chestnut-brown. 
Strongly pleochroic, the following being the scheme of pleochroism : — 
:i=brown ; b=yellow-browii ; r=;yellow. 
VI AC =16° to 22°. It is found at the manganese mines of Langban 
and Glakiirn in Sweden. 
In the following table I give those characters that have been ascer- 
tained for the yellow and brown pyroxenes of the rocks associated 
with or forming part of the gondite series. Since I have inserted in this 
list all the occurrences I have noticed of such pyroxenes in these rocks, it 
will be understood that they are of comparative rarity, considering the 
large number of occurrences of rocks of this series that are known. 
Of these occurrences, 1, 2, and 4 are in rocks that are in all probability 
of igneous origin, whilst 5, 6, and 8 are probably of metamorphic origin. 
No. 3 can be doubtfully regarded as of metamorphic origin, as it 
1 R. Mirtizelius, quoted by Sjogren, Bull G. Inst. Upsala, II, p. 77, 100. (1894), [Dana ] 
