of' Several Minerals. 243 



34 Apophyllite, from Iceland, crystallized and easily cleavable, 2.335 



"35. Mesole, from Faroe, 2.370 



36. Petalite, large cleavable individuals in a granular composition, 2.440 



37. Hemi-prismatic Felspar Adularia, white and perfectly trans- 

 parent, from St Gothard, 2.559 



38. Hemi-prismatic Felspar, semi-transparent, of a fine clove- 



Pr , 

 brown, perfectly cleavable, particularly parallel to — (P of Haiiy,) 



from Norway, 2.583 



39. Hemi-prismatic Felspar, the Labradorite, from Norway, 2.591 

 "40. Albite, white, faintly translucent, from Chesterfield in Mas- 

 sachusetts, the siliceous spar of Hausmann and Stromeyer, 2.612 



This variety does not show the re-entering angles formed 

 by the faces of the most distinct cleavage, (P of Haiiy,) like 

 the crystals of albite from St Gothard and other places, be- 

 cause it is composed parallel to this face in the manner de- 

 described by Professor Mohs.* The individuals are very 

 thin between the two opposite faces of P; when broken across 

 in the direction of Pr -f- <x, (M of Haiiy,) they exhibit the 

 slight salient and re-entering angles produced by the meeting 

 of the less distinct faces of cleavage, parallel to M. The 

 same frequently takes place in other varieties of albite, for in- 

 stance, the reddish-white one, from the syenite of Dresden. 



•41. Albite, small, perfectly transparent crystals, from Oisans, 

 where they occur along witli anatase, 2.614 



*42. Albite, larger crystals than the preceding variety, white, 

 translucent, from St Gothard, 2.633 



*43. Labradorite, from America, with a bright play of colour, 2.751 



•44. Labradorite, bluish-grey without bright colours, and hav- 

 ing rather an imperfect cleavage, from Siebenlehn in Saxony, 2.714 



*45. Labradorite, in every respect similar to the preceding, as- 

 sociated with the serpentine, No. 4, and hemi-prismatic Schiller- 

 spar, No. 3, from Monteferrato, 2.714 



'46. A similar variety, associated with hornblende, from Ross- 

 wein in Saxony, 2.714 



*47. A green nearly compact variety, very much of the same de- 

 scription, and probable belonging to the species of labradorite, asso- 

 ciated with the grey hemi-prismatic Schiller-spar, No. 6. 2.697 



*48. A Tetartu-prismatic kind of felspar, faintly translucent, yel- 

 lowish-white, in twin-crystals, joined parallel to the face of perfect 

 cleavage, from St Gothard, 2.553 



•49. Another specimen of the same, 2.548 



" Treatise, vol. ii. p. 257, Fig. 88. 



