i6i Natural BJlory of Iron. [Book VI. 



iron being found in the center of a vaft Jract of level 

 land, where there are no mountains, nor even the 

 fmalleft ftone, within a confiderable diftance, project- 

 ing above the fur face of the earth, is referred by the 

 y/riter of the article in queftion to an ancient volcanic 

 explofion, of which there are forne veftiges near it. 

 The fame fuppofition is urged with equal probability to 

 account for the production of another mafs of native 

 iron, in the fhape of a tree with its branches, which the 

 fame author aflerts, on indubitable authority, is known 

 to exift in tliefe immenfe forefts. Some fpecimens of 

 the iron were prefented to the Royal Society, who 

 afterwards depofited them in the Britilh Mufeum. 

 That large mafies of iron were really obferved in thefc 

 fituations there is no reafon to doubt, but I fhould ra- 

 ther attribute the fuppofed imprefiions to accidental 

 refemblances. 



The largeft quantities of iron ores are in a calciform 

 ftate, as in ochres, bog ores, &c. which are difpofed 

 in ftrata, in the manner of Hones. The astites, or 

 eagle ftones, are a variety of the bog ores ; they arc 

 in different forms, commonly oval or polygonous, 

 compofed of concentric layers difpofed round a nu- 

 cleus, which is frequently moveable in the center of 

 the ftone. The haematites, or blood ftones, are named 

 from their colour, which is commonly red. The load T 

 ftone is a dull iron ore, the varieties of which are dif- 

 tinguifhed by their colour. 



Emery is a grey or reddifh iron ore ; it is very hard 

 and refractory, and is found in abundance in the iflands 

 of Guernfey and Jerfey. It is reduced into powder in 

 mills, and in this ftate is u fed to polifli glafs and me- 

 tals. Spathofe iron ore is a calx of iron combined 

 carbonic acid} it is ufually of a white colour. 

 4 Nature 



