390 DALE— CAMBRIAN MANGANESE DEPOSITS OF [April 25, 



The paragenesis of minerals within the nodules is as follows : 

 Calcareous or carbonate material with probably synchronously 

 formed hematite, barite veining, chloritization replacement, and 

 finally calcite as vein or replacement material. 



219 A 3 is a green shale bed, 3 feet in thickness, lying conform- 

 ably above the Cryptozoon nodular bed. For the most part this bed 

 consists of a hard fissile green shale which breaks with a conspicuous 



Fig. 14. Photugraph of manganese carbonate nodules extracted from 

 shale 219 A4, natural size. Top, side and sectional views. 



conchoidal fracture. 3 inches above the Cryptozoon bed is a layer 

 containing fragments of trilobites which according to Prof. G. van 

 Ingen are probably to be identified as Protolenus harveyi. Barren 



