528 The American Naturalist. [June, 
mechanical means so as to leave a kernel with the shape of a 
Carlsbad twin. The cleavage of the mineral parallel to oP and 
CO r CO are inclined to each other at an angle of 90* 3'. Between 
crossed nicols plates cut parallel to oP show twinning lamellae 
of variable breadth extinguishing at 1^—31^''. Sections 
parallel to 00 P 00 possess an extinction of 5^ — 6'^. A chemi- 
cal examination of purified material gave: 
SiO, AIO3 CaO K3O Na„0 H.O Sp. Gr. 
61-35 23.10 3.02 5.34 7.11 .09 2.63 
Its composition corresponds to An, Or^.i Ab,.02. Since the 
mineral is undoubtedly triclinic Hyland would call it soda 
microcline as suggested by Brogger.— Intermingled with a few 
New Jersey, Mr. Eyerman' records the analysis of calamine 
from Friedensville, N. J., and of apophyllite from St. Peter's, 
Chester Co., Pa., as follows : 
SiO, Fe,03 QnO CaO K,0 RO 
Calamine, 24.32 2.12 65.05 7.86 
Apophyllite, 51.63 25.42 6.25 16.58 
— The same writer' describes large crystals of pjrite, chalco- 
pyrite, apophyllite, stilbite, garnet and smaller crystals of ^r^/- 
cite, orthoclase, pyroxene, aragonite, masses of pyrallolite and 
erythrite and needles of byssolite in calcite, all from the shafts 
of a magnetic mine at French Creek, Pa. The stilbite gave 
on analysis : 
SiO, ALO3 Fe.Os CaO MgO K,0 Na^O H,0 
58.00 13.40 tr. 7.80 r.40 1.03 tr. 18.30 
— Abnormally developed crystals of pyrite from these mines 
are mentioned by Mr. Penfield' as being lengthened in the 
direction of one of their axes as to present tetragonal sym- 
metry with all the planes terminating at the extremity of the 
extended axis curved. The crystals are either simple octa- 
hedra or octahedra in combination with pyrotoid faces. It is 
thought that the abnormality may be due to the development 
of the planes of the form V., O.— Crystals o{ gypsum from the 
salt marshes of Batz, Loire-Inferieur, France, are so associated 
- Notes on Geology and Mineralogy, Proc. Acad. Nat. Sci., Phila. Feb. 26, 
1889, p. 32-35- 
^. "'SV\ ^'^i^e'-alogy of the French Creek Mines in Pennsylvania. Read before 
the N Y. Acad, of Sciences, Jan. 14, 1889. 
