188 PHYSIOGRAPHY. 



Erinite. 



firmly cohering, so that they may easily be separated from 

 one another. These layers themselves are very compact, 

 exhibiting an uneven or imperfectly conchoidal fracture, and 

 traces of cleavage.* 



Color, a beautiful emerald green, slightly inclining to 

 grass-green. Streak green, but paler. It is slightly trans- 

 lucent on the edges. 



Brittle. Hardness =4-5 . . . 5-0. Sp. gr.=4-043. 



1. Analysis. 

 By TURNER. 



Oxide of copper . . . 54-44 



Alumina . . . 1-77 



Arsenic acid . . . 33-78 



Water . . . 5-01 



2. It is associated with other species of arseniate of copper, and occurs 

 in the county of Limerick in Ireland. 



ERLAN. 



Massive : composition granular, also impalpable and slaty. 

 Fracture splintery and uneven. 



Color greenish grey. Lustre feebly vitreous to dull. Streak 

 white, and possessing a resinous or oily lustre. 



Hardness = 5-5 ... 6-5. Sp. gr. = 3-0 . . .3-1. 



1. Analysis. 

 By GMELIN. 



Silica . . ^ . . . 59-8 



Alumina ..... 15-9 



Lime ...... 15-7 



Oxide of manganese . . 5-6 



Soda 3-0 



2. It occurs associated with Mica at Schwarzenberg in Saxony, form- 

 ing a mountain mass. 



* These plates form crest-like aggregations. A circumstance which 

 greatly increases the difficulty of observing the regular forms, is the 

 want of lustre ; the surface of the concentric layers being quite dull, 

 while there is only a slight degree of resinous lustre on the fracture. 



