What is this rock?

[Marian714]

Found this in the Absoroka Range of the Rocky Mountains in Wyoming. This range was formed by volcanic action. Weighs 32.2 pounds & is about 16” x 12” x 6” thick. Photos show standard 8.5x10 paper for scale.
Appears to have some kind of crystals mostly whitish in color with faint purple in spots & with the outside appearing to Have been “melted” (volcanic action?)

 

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[paleomaxx]

It's a nice quartz geode and it is related to the volcanic action, but the quartz itself formed after the surrounding rock had cooled. Water with dissolved silicates would percolate into gas pockets left inside the solidified rock and over time precipitate into quartz crystals. Larger crystals like the one in your specimen formed from hydrothermal water that came from deeper in the crust as opposed to water from the surface.

 

[flinger]

Looks like a geode or part of one. Research them to make sure.

 

[flinger]

It's a nice quartz geode and it is related to the volcanic action, but the quartz itself formed after the surrounding rock had cooled. Water with dissolved silicates would percolate into gas pockets left inside the solidified rock and over time precipitate into quartz crystals. Larger crystals like the one in your specimen formed from hydrothermal water that came from deeper in the crust as opposed to water from the surface.

Didn't read your post before I posted...seems you nailed it.

 

[Marian714]

Thank you so much!!! This is the first time in this site. VERY, very impressed!
Been trying to get into treasure hunting for a while now. Found this site & the app to go with it. Thought, what the hell, see if these guys can help. So I joined & posted.
Wow!!! Again, very impressed!!!
Thank you all for your assistance. I’ve had this Rick for about 10 years and no one that I asked could help me. I hope that in the future I can pass it forward!
Wishing you all, all the best for the holidays and a blest New Year!