F, A. Genth’s Contributions to Mineralogy. 251 
I found the pure mineral to contain : 
Silicic acid, - - + 2490 contains 12°93 oxygen = 1°20 
umina, - - - 21°77 33 10°17 1155 1-08 
Sesquioxyd of iron, - 460 . 1°38 
Oxyd of iron, = - - 24°21 “ 5°37 
Oxyd of manganese, - 1°15 * vas 10°74 t 
Magnesia, - + - 12°78 mf 511 
Water, - - - - 10°69 - 9°41 0°87 
The oxygen ratio of RO: R, O,: SiO, : HO being 
1: 1:08: 1:20: 0°87, the ratio of the 
equivalents would be =12 : 4: 8: 10,and considering 
alumina and sesquioxyd of iron as replacing silicie acid th 
formula = sR, (3) stom, or perhaps better a5) 3 +3He 
9. Pholerite. 
A mineral has been observed in several of the coal mines of 
Schuylkill county, Pa., under similar circumstances to those, 
identical, notwithstanding the differences between my own an 
Guillemin’s analyses. 
At Tamaqua it is found in scales of a yellowish white color, 
which, however, can be easily removed by dilute chlorhydric 
acid, and near Pottsville in snow white nacreous scales o 
pearly lustre. . 
Under the microscope the scales appear to be clinorhombic 
With the planes 22 predominating and —1i indicated by the trun- 
cation of the acute basal edge of the right rhomboidal prism. — 
I have made several analyses of the mineral from a 
a5 in its original state and after purifications by dilute chlor- 
Yydriec acid. j 
The analyses were made by fusion with carbonate of soda, as 
well as with concentrated sulphuric acid ; the silicic acid separa- 
ted by the latter method dissolved completely in boiling carbon- 
> a. The alkalies were determined by J. Lawrence 
Smith’s method: 
* Il. Ht. Iv. 
Original Mineral. “extracted by Chiorhydric Acid. Calculated. oh 
; By Na0.CO,  ByNaQCOz ByHOSO, 21; 5i,+6H 
Silicic acid, “ = 46-93 46 98 4681 4706 
Alumina, 9 3965 8956 89200 
Geguinydof ie 018 
Sem ot ¢ 3 i oa 
Potash, - — . eee en i 8 tc ee 
Water, = - 1398 13°69 13-91 13-71 
99°92 10049 100 45 100-00 
ieee analyses show that many of the varieties of the so-called 
lin belong to pholerite. : 
