G6 



The Badland Formations of the Black Hills Region 



Constituent. 



Silica (S1O2) 



Alumina (AI2O3) 



Ferrous oxide (FeO) 



Lime (GaO) 



Magnesia (MgO) 



Loss on ignition 



Volatile 



Alkali 



Moisture 



Total 



Per cent. 

 55-45 

 18.58 

 3.82 

 3.40 

 3-5o 

 8.80 

 5-35 



98.90 



Per cent. 

 57.00 



17-37 

 2.63 

 3.00 

 3.03 

 9-50 

 5.85 



98.35 



Per cent. 

 58.72 

 16.90 

 4.00 

 4.06 

 2.56 

 8.IO 



2. II 

 2.3O 



98.45 



Fairburn, and analyses 4 and 5 of material from near Argyle* 

 Volcanic Ash. Volcanic ash has been mentioned in the 

 description of the various formations. It is made up of minute 

 fragments of natural glass. The ash, if its individual particles 

 are of uniform size and have sharp cutting edges, has economic 

 value as a polishing powder or in the prepared state as an im- 

 portant constituent of abrasive soaps. Several deposits of this 

 character have been observed within the Black Hills region, the 

 best known ones being near Oelrich and at the fullers' earth 

 locality near Argyle. 



Bone Phosphate. The fossil bones found in the badland 

 deposits, like the bones of present day animals, generally contain 

 much phosphate. There is little reason, however, to believe that 

 the phosphate can be utilized commercially. Men speak of the 

 abundance of the fossil bones, but it should be stated that this 

 is more particularly from the viewpoint of the scientist inter- 

 ested in their educational value rather than that of the manu- 

 facturerer of commercial bone products. There seems never to 

 have been any very great tendency for the phosphate to leach 

 out from the bones and concentrate into beds. In a few in- 

 stances the matrix enclosing bone material has been analyzed, 

 but so far as I am informed, the amount of contained phosphate 

 lias been small. Mr. D. D. Owen of the Owen Geological Sur- 

 vey, in an analysis of the matrix of the skull of an Oreodon 

 gives the phosphoric acid as 1.80 per cent, and for the matrix 



*lRdes, Beinrich. The Fullers' Earth of South Dakota. Trans. 

 Am. Inst. Mln. Eng., Vol. 27, 1897, pip, 333-335. 



