PHYSIOGRAPHY. 



Gmelinite Graphic Gold. 



233 



4. It would appear that the newly proposed Ledererite, from Cape 

 Blomidon. Nova Scotia, is a variety of Gmelinite. It is described by 

 Mr. JACKSOIV as occurring in regular six-sided prisms, whose terminal 

 edges are truncated, the truncating planes inclining to the prismatic fa- 

 ces under angles of 180, i. e. y on y f (of the above figure) =? 80 ; a 

 difference not very considerable, when it is considered that the common 

 goniometer was employed. The crystals, besides, are mentioned as hav- 

 ing the longitudinal striae upon the prismatic faces. Sp. gr. = 2-169. 

 Hardness nearly the same as Feldspar, though from the circumstance 

 that Mr. BROOKE considered the mineral as Apatite, it seems probable 

 that it must be somewhat lower. The crystals are transparent, or only 

 translucent ; white, or tinged with flesh-red. Lustre vitreous. Ac- 

 cording to Mr. HAYES, it consists of, Silica 49-470, Alumina 2T480, 

 Lime 11-480, Soda 3 940, Phosphoric acid 3-480, Oxide of iron 0-140, For- 

 eign matter 0-030, Water 8-580, Loss 1-400. This mineral occurs in 

 trap, with Analcime and Stilbite. 



GCETHITE. (See Limonite.) 



GRAPHIC GOLD. Prismatic Antimony-Glance. 

 MOHS. 



Primary form. Right rhombic prism. M on M = 107 

 44'. 



Secondary form. 



Fig. 215. 



P on al 

 P on 2 

 P on cl or cl' 

 P on c2 or c2' 



P on c3 orc3' 132 45' 

 MonA - J26 08 

 /on h ' T 90 00 



Cleavage parallel with M highly perfect ; with T per- 

 fect, though not so easily obtained. Fracture uneven. 



