104 PROCEEDINGS OF THE SAIXT LOUIS MEETING 



not indurated. Possibly they may be due to the descent of calcareous water 

 which has flocculated the underlying clay. 



Reply by author (Dr. W. A. Tabr) to questions: The fact that oolites might 

 form from a colloidal silica gel at times and chert at other times can be ex- 

 plained by the rate of accumulation of the silica and the inclosing sediments, 

 the movement of the water, and the amount of silica added. In the case of 

 shales, the muds are added so fast in agitated waters that when the rate of 

 addition of silica is sufficient oolites may form. In limestones the slow rate 

 of accumulation permits the growth of large aggregates of silica. At other 

 times the silica added goes down as the colloidal matter of the clay. 



Remarks were also made by Dr. R. M. Bagg. 



GLAUCONITE IN DOLOMITE AND LIMESTONE OF MISSOURI 

 BY W. A. TARR ^ 



{Abstract) 



Glauconite occurs in grains in the Burlington limestone (Mississippian) and 

 in similar form, but in much larger amounts, in the Bonne Terre dolomite 

 (Cambrian) in southeastern Missouri. It is associated with the lead ores in 

 that district and was long mistaken for chlorite. The glauconite was deposited 

 at the same time as the dolomite. A suggestion as to its origin is made. 



Presented in abstract extemporaneously. 



DISCOVERY OF FLUORITE IN THE ORDOVICIAN LIMESTONES OF WISCONSIN 



BY RTJFUS MATHER BAGG 



(Ahstract) 



Fluorspar has never been recorded from the Ordovician galena beds in Wis- 

 consin, though its absence has been repeatedly mentioned in the various geo- 

 logical reports of the State. References to this are cited and a brief discussion 

 of this common associate of zinc-lead ores. 



A short description of the occurrence of this mineral and some theoretical 

 considerations as to its probable origin are given. 



Other minerals present in the quarries where this mineral occurs are shown 

 and the order of their deposition explained. 



Presented in abstract extemporaneously. 



Discussion 



Dr. W. A. Tarr : Fluorite is found in crystals up to two inches across in 

 geodes in the Saint Louis (Mississippi) limestone. It is usually the very last 

 mineral to be deposited. 



OCCURRENCE OF A LARGE TOURMALINE IN ALABAMA PEGMATITE 

 BY FRANK R. VAN HORN 



(Abstract) 

 In the vicinity of Micaville, Randolph County, Alabama, there are many 



1 Introduced by E. B. Branson. 



I 



