1825.] '] . Scieniijic Notices — Mineralogy ^ 231 



terminated by a four-sided acumination, whose sides rest upon 

 the edges of the prism. The lateral planes of the prism are in 

 every respect similar, and none of them are streaked. Some- 

 times these prisms are found combined together in the form of 

 twin crystals. '. 



The ordinary harmotome he found to be composed of 



Silica. ■ .■.".;■.. 44-79 



Alumina..'..../.'.;.?:.:;,..'...';.,. 19-28 

 ' Barytes. ...... ..:...:.....:.:. ;M7-59 



Lime 1-08 ' 



Oxides of iron and manganese 0-85 



Water 15-32 



98-91 



The specimen which he analyzed was obtained from the Schif- 

 fenberg, a hill in the neighbourhood of Giessen. Like the pre- 

 ceding, its crystal is a square prism, but it presents itself under 

 a variety of modifications. Its matrix is also a basaltic amyg- 

 daloid. 



The calcareous harmotome appears from his analysis to be a 

 compound of 5 atoms of bisilicate of alumina + 1 atom of qua- 

 drosilicate of lime + 8 atoms of water. The barytic harmotome 

 appears to contain a similar number of atoms of bisilicate of 

 alumina and of water, combined with an atom of quadrosilicate 

 or trisilicate of barytes. — (Annalen der Physik.) 



4. Cadmiferous Sulphuret of Zinc. 



A specimen of common blende, of a reddish colour, passing 

 into lead grey, was found by Dr. R. Brandes to be composed of 



Sulphur 33-838 



Zinc 58-150 



Cadmium 0-932 



Iron 7-628 , 



100-548 

 (TrommsdorfF's Neues Journal der Pharuiacie.) 



5. Sulphuret of Lead atid Antimony . 



TrommsdorfF found a specimen of this ore to be composed of 



Sulphur 20-9 



Antimony 22-4 



Lead 49-0 



Iron 4-0 



Manganese 2-0 



Copper 1 -0 ' 



Loss 0-7 



100-0 



