MODE X. IRON-STONE. 



STRUCTURE III. AMYGDALITE WITH OPEN PORES. 



This substance abounds in the high upland of 

 Mexico, where it is of a reddish colour, and is the 

 tetzontli used in building. As that region abounds 

 with volcanoes, it is probably a lava. 



MODE X. IRON-STONE. 



Texture, compact, granular or earthy, some- characters, 

 times undulated. On the surface of English 

 hills composed of this substance, it often pre- 

 sents a singular ornamented appearance, as if 

 derived from pinnae, or some other long py- 

 ramidal shell, with transverse bars ; and is some- 

 times covered with yellow rust from the decom- 

 position of the iron. 



Hardness, basaltic. Fragments, amorphous, 

 rather sharp. 



Weight, siderose. 



Lustre, dull, opake. 



This substance forms many small chains of sues. 

 hills in England, as in Surry, &c. and in other 

 countries, yet has scarcely been identified in 

 books of mineralogy. Ferber, in his_ orycto- 

 graphy of Derbyshire, mentions iron-stone as 



