Basalt Photos
Cochise College
Photos of Rocks       
Igneous Rocks
Geology Home Page
Roger Weller, geology instructor                   copyright 2011

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.


basalt                                                                                                                              thomsonite1

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