80 



PHYSIOGRAPHY. 



Nepheline Nephrite. 



rather rough. The variety Elaolite possesses a dark-blue 

 color, passing into green, grey and brown. 



1. The old species Elaolite appears to be, with justice, incorporated 

 with Nepheline, on account of their resemblance in hardness and spe- 

 cific gravity. The Cavolinite and Davyne, also> fall within the present 

 species, differing from it only in a somewhat diminished specific gravity, 

 and in the surface of the crystals. The sp. gr. of the former is 2-1 : its 

 crystals are opake, and possessed of a pearly lustre, that of the latter 

 = 2-25 . . . 2-3, with surfaces of .crystals which are dull. 



2. Before the blowpipe, upon charcoal, its edges are rounded off. It 

 yields a colorless vesicular glass, but cannot, be melted into a perfect 

 globule. Fragments of it, thrown into nitric acid, lose their transparen- 

 cy, and assume a nebulous appearance. 



4. The crystallized variety occurs at Monte Somma, in the cavities of 

 itnestone rocks, ejected by Vesuvius, along with Idocrase, Garnet and 

 Mica. It has also been found in nanow veins, traversing a kind of ba- 

 salt or lava at Capo di Bove, near Rome, sometimes associated with P.y- 

 roxene. The Cavolinite and Davyne are found in the lavas of Vesuvius. 

 The massive variety, or Elaolite, occurs near Laurig, Stavern and Fred- 



eriksvtlrn in Norway, imbedded in sienite, with Zircon and Sphene. 







NEPHRITE. Uncleavable Pe ta li ne-Sp a r. 



Massive : composition impalpable. Fracture coarse 

 splintery ; in some varieties slaty in the great. 



