410 Minerals recently investigated by M. Hermann. 
3. Ruoponrre, on Manganese: Spar. 
Rhodonite was long since shown to be a manganese augite, 
and the Fowlerite of Shepard is recognized by Hermann as giv- 
ing the angle of augite; M:M=87°6’. Hermann has analyzed 
the Stirling, N. J., mineral with the following result, 
Si Fe Mn 2 Ca Meg 
4648 723 81°52 585 450 3:09 loss by ignition, 1:00=99°67 
Oxygen, 2413 1°60 R06: Oba 2998) 88 ; 
giving for the oxygen ratio for protoxyds and silica 12°31; 
24:13, or very nearly 1:2, as in the received formula Mn: Siz. 
He obtained the specific gravity 3°63. 
Hermann has also analysed the manganese spar of Cumming+ 
ton, Massachusetts, and has concluded that the mineral instead of 
being a manganese augite is a manganese hornblende, that is, 
has the oxygen ratio 4:9 and formula Mns Sis. x; 
His analysis gave 
Si Mn, trace of Fe Oa Mg 
48-91 46°74 2-00 235=100-00 
Oxygen, 25°38 10°37 0-57 0-91 
The result affords the oxygen ratio for protoxyds and silica 
11-85 : 25-38 or very closely 4: 84, which is as near augite as the 
hornblende ratio. He unites with his mangan-amphibol, Thom- 
son’s sesquisilicate of manganese from Stirling, which according 
to Thomson has the angle 123°30’, which is nearly that of horn- 
blende. But Thomson’s analysis proves the crystallographic 
measurement of little value, since it makes the species a man- 
gan-augite—it giving 
Si 42-40 Mn 50°72 Fe 6-76 
or even less silica than required for an augite, instead of the ex- 
cess which would make it a hornblende. 
he mineral of Cummington often contains disseminated 
through it visible points or grains of silica, and if in visible grains, 
there will be also invisible silica, and enough to account probably 
for the hornblende composition. M. Adolph Schlieper, now of 
Lowell, Mass., has examined and analyzed the Cummington min- 
eral, from specimens placed in his hands by the writer, and he at- 
tributes the excess of silica to this source. His analysis gives the 
oxygen proportion 11-36 to 26-6, or quite closely 4:9. He found 
the mineral to be partly soluble in acids and by this means sep- 
arated it into an insoluble portion 90:15 per cent., a soluble 9°85. 
The insoluble part afforded : 
i Mn Oa Mg Fe 
51-21 42°65 2-93 trace 43410118 
Oxygen, 26.6 9°56 0-84 096 
The soluble part consisted of carbonates as follows 
~ Mn e ‘a Mg 6 H and loss. 
5052 8°60 8717 2°44 1:27=100 
