Kraus and Hunt — Sulphur and Celestite. 239 



that all of the calcium and magnesium oxides are doubtlessly 

 present as carbonates and not in part as sulphates. 



The unusually high percentages of strontium oxide and 

 sulphur trioxide are extremely interesting. If we consider the 

 small amount of barium oxide present as isomorphous with the 

 strontium oxide, we obtain the following proportion : 



| lao IS'] |- : s °. e° V90 '> = ! : 1 -° 306 - 



These values would indicate that the sulphur trioxide is 

 combined with the oxides of strontium and barium and, hence, 

 evidence is at hand that the mineral celestite is present in 

 this uppermost layer to the extent of 1^32 per cent. The 

 results of the analysis are, therefore, in harmony with what 

 has already been said concerning the structure and specific 

 gravity of the rock. 



The very small amount of the combined oxides of aluminium 

 and iron, namely 0'37 per cent, would preclude any appreci- 

 able quantity of pyrite or marcasite being present. It is, how- 

 ever, significant, as will be seen later, that organic matter and 

 a trace of hydrogen sulphide were noted. 



Descending into the quarry, not only do the strata become 

 more porous and cavernous but at various levels water con- 

 taining a considerable amount of hydrogen sulphide is encoun- 

 tered. As said, the porous layers contain native sulphur 

 associated with celestite. Sherzer in discussing the probable 

 origin of the sulphur at this quarry rightly refers the same to 

 the hydrogen sulphide, which is to be observed to a very large 

 extent in Southern Michigan. In the immediate vicinity of 

 the Woolmith quarry most of the wells show varying amounts 

 of it. These wells are from 18 to 20 feet deep and after pass- 

 ing through the drift penetrate rock to the extent of two to 

 four feet. The layer, which is doubtlessly encountered, is the 

 one called Bed A, an analysis of which was just given. 



Sherzer thought that the hydrogen sulphide might be due 

 to the decomposition of pyrite and marcasite, which were sup- 

 posed by him to be present in considerable quantities. The 

 analysis of the rock of Bed A. however, shows clearly that if 

 these sulphides of iron are present in the upper strata, they 

 must be present in amounts which are almost insignificant 

 when compared with that of strontium sulphate. In some of 

 the lower layers, in a few instances, pyrite has been noticed but 

 always in very small amounts.-- Its occurrence is also clearly 

 secondary. Without a doubt we are dealing with descending 

 waters at this locality. 



It is also of vast importance to call attention to the fact that 

 when the rocks of the various layers in this quarry — the same 



