T44 Elements of Mineralogy* 



the Philofophical Tranfadions for 17791 p^ 

 35, by Mr. Ed-ward King, who found a ftony 

 concretion of this fort round iron, which had 

 been long buried in the fea. 



Mr. Gadd, in the Swedifh Memoirs for 

 1770, relates, that Mr. Rinman had found a 

 fimilar concretion round an old anchor that 

 had long been depoiited in the fea. He alfo 

 adds, from his own experiments, that dephlo- 

 gifticated calces of iron, and particularly 

 folutions made by the mineral acids, have not 

 the fame binding power, but, on the contrary, 

 make loofe concretions, as Dr. Higgim has 

 alfo fhewn in a late very ufeful treatife on 

 cements. 



To this fpecies may be added the blacky 

 heavy* glojfy Quartz of Cronjhd* 53, which 

 he fays is found in the mine of 6/J/i in Su- 

 dermanland, and contains a large proportion 

 of iron. 



Compound Species in nvhich the Siliceous Genut 

 predominates. 



SPECIES I. 



Compounds of the different Species of the Sill-, 

 oeous Genus <with each other. 



I VARIETY, 



