TAB. LXI. 



FERRUM argillaceum. 

 Argillaceous Iron Ore. 



Class 3. Metals. Order 2. Mixed. 

 Gen. 7. Iron. Spec I. Argillaceous. 



Div. 



Syn. Common argillaceous Iron-stone. Kiriv.v.173* 

 Lowland Iron Ore. Bab. 199. 



Among other iron ores a great deal of the sort above 

 figured is used. It is chiefly iron mixed with clay, produ- 

 cing 30 to 50 per cent, as we have heard. This variety is ad- 

 mired for its being divided into polygonal columns by cal- 

 careous spar. It is found in round or compressed lumps, 

 called by the miners cats' heads or cats' scalps. 



It appears that the iron clay in lumps has cracked inter- 

 nally, and that calcareous earth has crystallized in the fis- 

 sures*. The upper figure shows it as it commonly appears 

 when cut. Bitumen is sometimes contained in the cracks, 

 as are various other substances. In the middle figure the 

 calcareous spar is mixed with blend, and is more concen- 



* These divisions depend on the vicissitudes of wet and dry, hot and cold, and 

 approach to the nature of the Giant's causeway in Ireland, &c. 



