NOME XIX. BARYTIC ROCK. 139 



traversed by some veins of quartz. The fluor is 

 of various colours : green, violet, and reddish ; 

 yielding much phosphorescence when thrown on 

 hot iron, as well as a spathose acid gas, very acrid 

 and corrosive, when it is heated with vitriolic 

 acid. The barytes is white, with a slight tinge 

 of red, very pure, and disposed in large plates. 

 It is sometimes crossed with veins of a beautiful 

 pitch-stone, of a deep yellow, a little transpa- 

 rent, but sometimes opake, and resembling yel- 

 low resin. 



" The texture of this pitch-stone is rather 

 loose, and it seldom strikes fire with steel ; but 

 in its fracture it shows the conchoidal form, as 

 well as the convolved streaks of silex ; while 

 some, in a state of decomposition, leave a lilac 

 coloured earth, which cleaves to the tongue. It 

 appears that it is coloured by iron, for there ap- 

 pear, in some parts of this stone, grains of that 

 metal, which have given more intensity to the 

 colour of the pitch-stone in the adjacent parts. 



" On examining some of the fluors, it may 

 be observed that there have been successively de- 

 posited new layers of the same fluor, and of 

 quartz of different colours, till the cavity, in 

 which the first crystals were formed, was filled 

 up. This frequent mixture of different sub- 

 stances forms veins in zigzag ; because they fol- 



