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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 68 



Chalcedony was found in megascopic masses only once as a pur- 

 plish-gray filling of a cavity lined with calcite crystals. Its micro- 



FiG. 8. — Calcitb. Habit of largee colorless crystals 



scopic occurence in lime-silicate rock has been noted above. The 

 chalcedony is in the white earliest calcite in the calcite veinlet above 



