TAB. CV. 



FERRUM sulplmreum, decomponens. 

 Sulphuret of Iron, decomposing. 



Class 3. Metals. Order I. Homogeneous. 

 Gen. 7. Iron. Spec. 4. Sulphuret of Iron. 



Sulphuret of Iron, or Iron Pyrites, under certain changes 

 of atmosphere, forms Sulphate of Iron, or Green Vitriol, as 

 figured in tab. 23, and often falls to pieces with efflo- 

 rescence ; to prevent which, and to preserve curious spe- 

 cimens, we are obliged to keep them immersed in water. 

 The upper specimen was sufficiently protected by the dark, 

 partly crystallized, outward coat, from decomposing in the 

 common atmosphere of a room, in a damp neighbourhood ; 

 but soon after it was broken, the more porous parts put 

 forth curls of lightish-green vitriol, and at the edges chiefly, 

 sulphur. It still slowly decomposes, and has continued to 

 do so for some months: in time perhaps it may fall to 

 pieces, or remain a porous iron ochre, like the lower figure. 

 These specimens were found among a micaceous limestone 

 in a quarry near Godstone, in Surry, where they roll down 

 from the lop in great abundance. 



