404 E. 0. Ilovey — Cherts of Missouri. 



extraneous deposit. What appear to be the cross-sections of 

 these rods have nuclei of brown matter surrounded by clear 

 chalcedony, but sometimes several exactly similar nuclei string 

 themselves together within a common shell of chalcedony. 

 Between crossed nicols there is no line of demarkation between 

 these bodies and the matrix, all is granular chalcedony. I 

 hesitate, therefore, to refer these rods to sponge spicules. 

 Many of the Lower Carboniferous cherts are highly fossilif- 

 erous, being more or less crowded with the remains of crinoids, 

 brachiopods and corals. These remains, however, are calcare- 

 ous in nature and form a breccia with the chalcedony of the 

 chert as the cement, though in the cherts described by Dr. 

 Keyes* the fossils have been silicified. A specimen from this 

 group at Grand Falls, Newton County, shows several sections 

 of a branching form of Stromatopora and this genus also 

 occurs in chert from Sulphur Springs, Arkansas. The chal- 

 cedony occasionally shows a tendency to form concretionary 

 granules. In the specimen just cited there are true fibrous 

 sphserocrystals which give a black cross in polarized light. 

 The pronounced granular or oolitic character is confined to 

 five of the Lower Magnesian specimens in the suite under dis- 

 cussion. In some of these the chalcedony has formed granules 

 without any apparent foreign nucleus, while in others rounded 

 grains of quartz were the nuclei of deposition. Siliceous 

 oolite was noted by G. W. Featherstonhaughf in Wayne 

 County, Missouri (?), Tennessee and Kentucky and reported as 

 "silicified oolite" of Carboniferous age, but his stratigraphy is 

 not to be depended upon. Concretionary or granuliferous chert 

 is one of the three divisions made by A. Renard;}: in his study 

 of the Carboniferous cherts of Belgium. A preliminary micro- 

 scopical and chemical investigation of siliceous oolite was made 

 by E. H. Barbour and J. Torrey§ on specimens sent them from 

 Center County, Pennsylvania. Since then the rock has been 

 reported a second time from Tennessee! and it appears proba- 

 ble from an able discussion of the Pennsylvania oolite by Dr. 

 W. Bergt,!" which first came to the present writer's knowledge 

 some months after his own article** on the same subject had 

 been published, that several rocks from widely separated parts 

 of the world and described under other names really belong in 

 this category. Our specimens, therefore, add five localities for 



* Loc. cit. 



•j- Geol. Rept. of an examination of the elevated country between the Missouri 

 and the Red Rivers, 1835, pp. 54, 55. 



\ Recherches lithologiques sur les phthanites du calcaire carbonifere de Bel- 

 gique. Bull, de l'Acad. Rov. des Sciences, etc., de Belgique, II, xlvi, 1878, p. 494. 



§ This Journal, III, xl, Sept. 1 890, p. 246. 



I G. R. Wieland in the Mineralogist's Monthly, vol. vi, Nov. 1890, p. 2. 



^f Abbandlung d. Isis in Dresden, 15, 1892. 



** Bull. Geol. Soc. Am., vol. v. p. 627. 



