434 . DALE— CAMBRIAN MANGANESE DEPOSITS OF [April 25, 



morphosed grit. The roof proper consist of about 2 feet of very hard, 

 schistose rocks, termed 'blue stone' by the miners. Specimens of ore taken 

 from the mine are seen to be formed of uniform layers, having gray yellow- 

 ish, white, greenish and chocolate-brown layers." 



A reference by J. A. Phillips and Henry Louis (21 : 296) to the same 

 occurrence is as follows : 



" Beds of carbonate of manganese with some silicate, the outcrops of 

 which have been to some extent changed into black oxide, occur intercalated 

 between sandstones, grits and conglomerates of the Cambrian formation, and 

 have been mined to some extent ; the beds vary from one to two feet in 

 thickness, and yield ore, averaging about twenty-seven per cent, of metal, 

 which is used in spiegel making. These deposits are evidently symphytic and 

 belong to group b of that class." 



Phillips and Louis believe that these deposits were formed syn- 

 genetically but from precipitates in aqueous solutions. This deposit 

 suggests very striking similarities to the Manuels occurrence not only 

 mineralogically and genetically but also from the standpoint of 

 stratigraphy. 



Arkansas. — The Cason tract of the Batesville region, Arkansas, 

 presents certain petrological analogies to the Newfoundland occur- 

 rences. Dr. Penrose (20: 219) describes the ore as occurring 



" in lenticular layers, varying from an eighth of an inch to three inches in 

 thickness, and interstratified with an indurated red clay of a slaty structure. 

 Generally, however, the ore occurs in the shape of flat, lenticular concretions, 

 from a quarter of an inch to one inch in diameter, locally known as 'button 

 ore.' They have a concentric structure, are dull black on the outside and 

 bright on the inside and are imbedded in a red or brown, fine-grained and 

 more or less calcareous sandstone." 



Analyses of the ore run as follows : 



Mn 34-64 50.41 



Fe 4-88 7-56 



SiO, 25.65 12.67 



P^Og 0.58 0.06 



ALO3 3-79 • 1-37 



CaO 513 2.09 



Similar conditions to those postulated by Penrose for the ac- 

 cumulation of the manganese in the Arkansas region seem to me 

 to be applicable to the Newfoundland deposits. 



