Can't figure out what this is....

[PinchedDreamer]

Hey all. Been finding these on occasion, but didn't realize until recently that the bubbles within the vesicles are actually crystals. They are formed in the shape of their respective vesicle, have a glass like feel, and some are almost transparent. Most are an off-white/ pale yellow green, but vary from dark green, to almost colorless. All I have been able to find online, suggests that they are crystals formed in extrusive igneous rocks that cooled rapidly. Anyone have any ideas?

 

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[Eu_citzen]

Use one of the specimens and see if a knife will scratch the green stuff, repeat with quartz. I'm thinking prehnite or olivine.

 

[PinchedDreamer]

The green is actual coloring of the crystals themselves. I can bust one apart and post pics of individual crystals if that might help. It will have to wait a few hours though, as I'm on my way to the casino for dinner and an evening of throwing cash away in the name of someone's birthday. Wish me luck

 

[hvacker]

Conglomerate with maybe olivine (peridot) nodules. The green stuff should streak white if olivine and be hard.
I won't wish you luck at the casino because you might go back.

 

[Eu_citzen]

Conglomerate with maybe olivine (peridot) nodules. The green stuff should streak white if olivine and be hard.
I won't wish you luck at the casino because you might go back.

Good thought, but this is a volcanic rock. Vesicular basalt seems likely.