ORDER I. PBISMATOIDAL GYPSUM-HALOIDE. 61 



other, as their division depends upon the size of the grain 

 or composition in general Thus foliated Gypsum consists 

 of discernible granular particles, compact Gypsum of impal- 

 pable particles of composition ; scaly foliated Gypsum con- 

 sists of minute scaly particles, earthy Gypsum of a mealy 

 powder. Very thin columnar composition produces fibrous 

 Gypsum. 



2. Prismatoidal Gypsum-haloide consists of 



Lime 33-0. 



Sulphuric Acid 44-8. 



Water 21-0. BUCHOLZ. 



It is represented by Ca S 2 + 4 Aq, which corresponds to 

 32-91 of Lime, 46-31 Sulphuric acid, and 2078 Water. 

 The analysis refers to a variety of Fraueneis ; but most of 

 the rest very nearly agree with it. Before the blowpipe it 

 exfoliates, and melts, though with difficulty, into a white 

 enamel, which after a short time falls into powder. In a 

 lower degree of heat it loses its water and becomes friable, 

 so as to be easily reduced to an impalpable powder. If 

 mixed with water, this powder becomes warm, and soon 

 hardens into a solid mass. 



3. Compound varieties of this species form beds in se- 

 condary mountains, more sparingly in the older classes of 

 rocks ; they generally possess a considerable thickness, 

 though they are of a very limited extent in length and 

 breadth. It is less frequently met with in veins and beds, ac- 

 companying minerals of the orders Glance, Blende, Pyrites, 

 sometimes hexahedral Gold, &c. In its more peculiar re- 

 positories, it is accompanied by compound varieties of 

 rhombohedral Lime-haloide, hexahedral Rock-salt, by dif- 

 ferent kinds of sandstone and clay in alternating layers, in 

 the latter of which it also occurs in imbedded masses or crys- 

 talline groupes. Very often brine springs issue from the 

 rocks in its vicinity. In some places it is associated with 

 prismatic Sulphur and prismatoidal Hal-baryte. Simple 

 varieties are chiefly found in salt-works, also in abandoned 

 mines and old heaps, where they must be considered as 

 products of more recent formation. Of the organic re- 



