330 



DESCRFPTIVE MINERALOGY. 



Fig. 280. 



Composition. Meionite — Silica 45.53, alumina 32.73, lime 24.25, potash and soda 1 .82, 

 protoxide of iron 0.18 {Stromeyer). 



Scapolite — Silica 43.83, alumina 35.43, lime 18.96. water 0.03 (Nordenskiold). 



Wemerite — Silica 50.25, alumina 30.00, lime 10.45, potash and soda 2.00, protoxide 

 of iron 4.45, water 2.85 {John). 



Nuttallite, from Bolton, Massachusetts — Silica 46.30, alumina 26.48, hme 18.62, soda 

 with Uthia 3.64, water 5.40 {Thomson). 



Dipyre — Silica 60.00, alumina 24.00, lime 10.00, water 2.00 {Vauquelin). 



The formula for scapolite is probably 3Alj03Si+CaSi03. 



Geological Situation. In this State, it is almost exclusively confined to beds of white 

 limestone, in .which it is usually associated with sphene and pyroxene. The meionite is often 

 found in a red calcareous spar. It has not been observed, as in Norway and elsewhere, in 

 beds of magnetic ironstone and iron pyrites in gneiss. 



Essex County. Scapolite in imperfect crystals, and in masses having 

 an almost fibrous structure, occurs abundantly associated with pyroxene, 

 near Kirby's graphite mine, four miles northwest of the village of Alexan- 

 dria in Ticonderoga. It is white, greyish or greenish white and green. 

 The crystals are large, and the masses are cleavable, and sometimes 

 appear to be made up of long and slender crystals of the primary form. 

 This mineral also occurs in the town of Keene, in crystals in which the 

 primary planes are extinguished by the extension of the planes s, Fig. 

 280. The secondary form, therefore, can be distinguished only by the 

 inclination of the faces I :* s on s 90° ; s on I 122° 10'. 

 Lewis County. Near the Natural bridge, is a remarkable locality of the variety Nuttallite. 

 It occurs crystallized. The crystals are often very perfect and variously modified, but most 

 generally they are rounded on the edges as if by fusion. The colours are 

 white, bluish and dark grey ; and the mineral exhibits the high vitreous 

 lustre and the play of light peculiar to this variety. The specific gravity is 

 2.712. It is associated with pyroxene, sphene and apatite in a highly 

 cleavable variety of white calcareous spar. Among the crystalline forms 

 which have been observed at this locality, are the primary (Fig. 279), and 

 those represented in Fig. 281, in which the edges of the prism are re- 

 placed by narrow tangent planes, and the solid angles are also replaced 

 by planes ; 



Fig. 281. 



HL 



M. 



•Emmons. New-York Geological Report), 1837. 



k 



