Chap. VII.] 
MANG ANESE- MICAS. 
193 
calcium, and a trace of magnesium. The amount of manganese does not 
seem to be very large, whUst the AI2O3 is probably less than the Fe203 in 
amount, and the amount of CaO is considerable. Water, however, 
seemed to be absent. But for the latter fact the mineral might have 
been regarded as a variety of carphoUte in which a large portion of the 
MnO was replaced by CaO and a large portion of the AI2O3 by Fe203. 
I have mentioned this mineral in this place because of its outward 
resemblance to carpholite, but recognize that when it is analysed it will 
probably be found to be a different mineral, perhaps even one of the 
yellow manganiferous amphiboles. 
In E. Balfour's catalogue of the Rev. Mr. Muzzy's collection of 
minerals and rocks ^ there is a record of the occurrence of this min- 
eral in the Madura district ; whilst J. H. Nelson 2 in giving a more 
detailed accoimt of Muzzy's collection, mentions the occurrence of 
' karphoUte' near Puda-kudi, about 22 miles N.-W. of Madura. This 
record is to be considered doubtful. 
Manganese-micas. 
Very little work seems to have been done on micas characterized 
by the presence of a quantity of manganese sufficient to produce any 
appreciable efiect on the physical characters of the mineral. Nearly all 
the micas may occasionally contain a small amount of MnO, but this 
rarely affects the colour or other properties of the mica to an appreciable 
extent. There are, however, three micas containing manganese, to 
which separate names have been given. These are manganophyllite, 
caswellite, and alurgite. In this place we will also consider the mineral 
known as nianganchlorite, as it is difficult to tell from altered varieties 
of manganophyllite. Manganophi/llite is a manganiferous variety of 
biotite found at Pajsberg, Langban, and probably Jakobsbergj in 
Sweden. Its formula may be represented as follows : — 
(H,K)o(Mg.-M.i)2(Al,Fe)2{Si04)3, 
that of ordinary biotite being — 
;H,K)2(Mg,Fe)2(Al,Fe)2(Si04)3. 
The analyses given by Dana show 5*41 to 2r40% MnO. In colour 
the mineral is bronze to copper-red, with a pale red streak. In thin 
scales rose-red. The pleochroism is : — 
tl c (b, c) = colourless or pale yellowish led, 
j_ e l ;x) = deep reddish brcwn. 
1 CatAl. Govt. Central Mus., Madras, p. 3, (1855; 
2 'TheMudura Country pp. 15, 27, (1868). 
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