286 E. II. Kraus — Celestite- Bearing Rocks. 



Art. XX VI. — Occurrence and Distribution of Celestite- Bear- 

 ing Mocks ^ by Edward H. Kraus. 



In July, 1904, f I announced the fact that the mineral celes- 

 tite occurs quite extensively in a disseminated condition in the 

 dolomitic limestones and shales in the upper portion of the 

 Salina epoch. The celestite-bearing rocks studied at that time 

 were confined to localities in Central New York, especially 

 those near Syracuse. However, in describing the various 

 occurrences, the following statement was made : " I do not 

 doubt, whatever, but that its (celestite) occurrence in the dis- 

 seminated condition, as shown by the accompanying figures, is 

 just as extensive in the limestones of the Salina elsewhere, as 

 in the vicinity of Syracuse." J 



During the past summer, the Island of Put-in-Bay in Lake 

 Erie was visited. This island has become well known for its 

 interesting caves, among which is the celestite cave, popularly 

 known as " Crystal " or u Strontium " cave. The rocks of the 

 island have been assigned to the Lower Helderberg epoch. 

 Wherever they are exposed along the lake shore they present a 

 more or less porous appearance. There are a goodly number 

 of exposures in various places on the island away from the 

 shore, and even in such places many of the rocks have a struc- 

 ture which is so characteristic of the leached celestite-bearing 

 rocks of Central New York. Numerous specimens were found 

 lying on the surface, which possess cavities with a distinct 

 orthorhombic outline. A very careful search failed to reveal 

 celestite in the interior of such rocks, but the outline of the 

 cavities leaves no doubt, whatever, as to the mineral which had 

 previously occupied them. There is a very striking similarity 

 between these rocks from Put-in-Bay and those from various 

 localities near Syracuse, N. Y. In some instances it would be 

 difficult to tell which specimens were from either place, were 

 it not for the fact that those from Put-in-Bay are for the most 

 part a little lighter in color. 



The dissemination of the celestite in the rocks near the 

 surface in the Put-in-Bay region was principally, so far as I 

 have been able to ascertain, in the form of small but well- 

 defined crystals. Celestite has been known to occur for many 

 years at this locality, and also on some of the other islands in 

 the southwestern portion of Lake Erie. Nearly all text-books 

 on mineralogy mention these islands as important localities for 



* Eead in part before the Philadelphia meeting of the Geological Society 

 of America, December 30, 1904. 



f This Journal (4), xviii, 30-39, 1904. 

 X Ibid. (4), xviii, 33, 1904. 



