PHYSIOGRAPHY. 43 



Mica. 



in plates of moderate size, has been met with near Moriah upon Lake 

 Champlain: also black mica in the same region at Willsborough, and a 

 pinchbeck-brown variety in Lower Canada. An emerald-green varie- 

 ty, in minute scales, disseminated through quartz, occurs at Brunswick, 

 (Me.) Lepidolite, in beautiful varieties, exists at Paris, (Me.) where 

 it is often penetrated, as at Rozena in Moravia, by Rubellite : in small 

 quantities, also, at Middletown, (Conn.) under similar circumstances. 

 Finite is found at Lancaster, (Mass.) imbedded in Quartz, associated with 

 Andalusite, and at Haddam, (Conn.) with Chrysoberyl, Garnet, Tour- 

 maline, &c. 



APPENDIX TO MICA. 

 i. Tautokline Jlster-Mica. BREITHAUPT. 

 Primary form. Acute rhomboid. Pon P = 66 11' 20". 

 Cleavage perfect parallel with planes, tangent to the angles of 

 the base ; with the primary faces, imperfect. 



Lustre pearly. Color green, to greenish white. Having but 

 a single optical axis. Streak greenish-white. 



Flexible in thin laminae. Hardness (scale of BREITHAUPT) = 

 2-25 . . . 2-50. Sp. gr. =2-821 . . . 2-885. 



1. The foliated chlorite from Zillerthal, and a portion of the old species 

 Mica, belong to the present division. 



ii. Rubdlan Aster-Mica. BREITHAUPT. 

 Primary form. Acute rhomboid. P on P = 66 19' 50". 



Cleavage as above. 



Lustre pearly. Color brownish red to reddish brown. Optical 

 axis single. Streak the same as color. 



Brittle. Hardness (scale of BREITHAUPT) = 2-50 . . . 3-0. 



Isp, gr. 2-697 . . . 2-717. 

 1. This mineral is found only in the Mittelgebirge in Bohemia, 

 iii. Kuphone Aster-Mica. BREITHAUPT. 

 Primary form. Acute rhomboid. 

 Cleavage as above. 



Lustre pearly. Color green. Optical axis single. Streak 

 greenish- grey, pale. 



Flexible in thin laminae. Hardness (scale of BREITHAUPT) = 

 2-25 . . . 2 50. 



1. The Kuphone Aster-Mica occurs in serpentine, at Waldheim, 

 Kuhschnappel and Kursdorf in Penig. 



