Intelligence mid Miscellaneous Articles. i^l 



Silica 41-4 



Lime 48-6 



Alumina 2'5 



Magnesia 1*5 



Protoxide of iron 2'5 96'5. 



According to Brooke the crj^stalline system of this species is the 

 prism with a square base, terminated by a pyramid, the angles of 

 Avhich are 122° 55' on the summit, and 85° 2' on the sides. 



Since the discovery of the lime harmotome, gismondine has often 

 been compared with it. Gmelin has included it in this species, 

 and has concluded from his chemical researches, that it belongs also 

 to zeagonite and abrazite. The identity of these latter minerals, as 

 also of aricite and phillipsite with gismondine, has been shown cry- 

 stallographically by Brooke, so that most mineralogists consider 

 gismondine as a variety of lime harmotome. According to Kohler, 

 the crystidlization of the lime and barytes harmotome strongly re- 

 sembles that of gismondine. J\I. Kobell analysed a pure specimen 

 of gismondine from Capo di Bove ; the crystals of this substance 

 are brilliant and perfectly resembling those of harmotome, except that 

 the re-entering angles. The angles of the pyramid with four faces 

 are about 121°, as in harmotome. The angles of gismondine cannot 

 be accurately measured, because the crystals are composite and are 

 never very regular. 



The hardness of gismondine is nearly equal to that of quartz, be- 

 tween 7 and 7'5 ; that of lime harmotome is between 4 and 5. The 

 specific gra\'ity is 2'18; gismondine dissolves readily and com- 

 pletely in hydrochloric acid ; the mean of two analyses made by 

 M. Kobell gave — 



SUica 42-72 



Alumina 25-77 



Lime 7-60 



Potash 6-28 



Water 17*66 100-03. 



The formula of which is K Si* + 2 C Si^ + 12 A Si + 15 Aq, 

 or otherwise, ^ | gja + 4 a Si + 5Aq. 



It is evident, according to M. Kobell, that Carpi either analysed a 

 different mineral, or has given an incorrect result. 



Tlierc are several analyses of lime harmotome ; three arc below 

 stilted ; the two first are by Gmelin and Kohler, of the variety from 

 Marbourg ; the third is by Kohler of a variety from Cancl. 

 I. II. III. 



Silica 48-02 50-445 48-222 



Alumina 22-61 21-783 23-333 



Lime G'bG G'500 7-222 



Potash 7-50 3-949 3-889 



Protoxide of iron 018 



Water :_1^"75 16-8 15 17-555 



101-62 99-492 100221 



