Basalt Photos
Cochise College
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Roger Weller, geology instructor                       

wellerr@cochise.edu    copyright 2007
 

amygdaloidal basalt-1

thomsonite fillings
The mineral filling the vesicles in the basalt is thomsonite, a zeolite with a
radiating structure.  As the lava is weathered, the thomsonite nodules show
up as beach pebbles along the western shore of Lake Superior.


Photo is copyright free for non-commercial educational uses. 
Just credit photo to R.Weller/Cochise College.