PHYSIOGRAPHY. CLASS II. 



Compound Varieties. Renifbrm, botryoidal, sta- 

 lactitic, and other imitative shapes : surface gene- 

 rally rough, composition columnar. Massive : 

 composition granular, sometimes impalpable; strong- 

 ly coherent. By decomposition it becomes friable 

 and earthy. Crystalline coats and pseudomor- 

 phoses formed after crystals of rhombohedral Lime- 

 haloide. 



OBSERVATIONS. 



1. The present species and the preceding one, though they 

 essentially differ in several of their characters, are allied 

 with each other by such high degrees of natural-historical 

 resemblance, that in the present state of our information it 

 becomes necessary to unite them within one and the same 

 genus. This resemblance contains the reason why those 

 mineralogists, who have attended only to the external cha- 

 racters, though not always with sufficient accuracy, did 

 unite them into one single species. 



2. According to SMITHSON, a variety of the present spe- 

 cies from Derbyshire consists of 



Oxide of Zinc 65-20. 



Carbonic Acid 34-80. 



Its chemical formula is Zn C 2 . which corresponds to 64-64 

 oxide of zinc, and 35-36 carbonic acid. It is soluble with 

 effervescence in nitric and muriatic acid. Before the blow- 

 pipe it loses its transparency, but is infusible ; the carbo- 

 nic acid is driven off, and the residue acts like pure oxide 

 of zinc. It is negatively electrified by friction. 



3. The varieties of the present species in general share 

 the repositories of the preceding one. They are often ac- 

 companied by species of the order Malachite, and the ge- 

 nera Lime-haloide and Iron-ore. 



4. It occurs in the Bannat of Temeswar in Hungary, at 

 Raibel and Bleiberg in Carinthia, at Tarnowitz in Silesia, 

 at Medziana Gora in Poland, at Aix-la-Chapelle ; also in 



