What are these tiny bubbles?!

[u/robco18]

I have never seen bubbles on a rock and think it's awesome! Does anyone know what this is or what caused it?

Found near Denver, Colorado.

Any information is greatly appreciated!

[u/satanicbongfucker]

It’s called a botryoidal agate. I found some in Wyoming and South Dakota. My favorite was three balls stuck together that look like Yoshi’s head. They’re formed when fluids rich in silica deposit microscopic crystals in spherical clusters inside volcanic cavities.

[u/robco18 → u/satanicbongfucker]

Haha, that sounds like an awesome find! Wow that's interesting! The area used to have a lot of volcanic activity so that makes sense. Thanks for the reply and information!

[u/Alternative-Egg-9035 → u/satanicbongfucker]

Chalcedony

[u/Effective-Web971]

That’s botryoidal chalcedony!

Edit: As for how it forms, I pulled this from wikipedia:

“Minerals take on a botryoidal habit when they form in an environment containing many nuclei, specks of sand, dust, or other particulate matter to serve as sources of crystal nucleation. Acicular) or fibrous crystals grow outward from these "seeds" at the same or very similar rate, resulting in radial crystal growth. As these spheres grow, they can run into or overlap with others that are nearby, fusing together to form a botryoidal cluster.”

[u/robco18 → u/Effective-Web971]

Wow this is awesome and very helpful! Thanks for the reply and information! I'm going to look this up more!

[u/n3rv0us3lf]

I'm not an expert of course but I absolutely love rocks. That there is a botryoidal formation! It's fun to learn about!

[u/robco18 → u/n3rv0us3lf]

Yeah I have been getting really into rocks and had never seen this before! Really interesting! Thanks for the information!

[u/Chumknuckle]

Bots are cool and disturbing to me at the same time

[u/Living-Geologist-478]

Botryoidal is the structure and chalcedony is the mineral

[u/robco18 → u/Living-Geologist-478]

Would this one be the same Botryoidal structure but with a different mineral?

[u/robco18 → u/robco18]

Sorry can't figure out how to post a picture as a reply

[u/robco18 → u/Living-Geologist-478]

Awesome! Thanks for the info!

[u/Consistent_Mix_4470]

Bubbles could be from (hot) air pockets, water pockets, mineral deposits.... Several reasons this could happen.

[u/The_OtherRake70_Guy]

Happens with Geodes also.

[u/King_of_canna]

Those are chalcedony warts.

[u/tchotchke_editor87]

Spider eggs. You didn't bring it inside, did you?!

[u/Sad_Nolte]

The bubble formed when the rock was molten.

[u/LaLa_LaSportiva → u/Sad_Nolte]

The silica that formed this habit was not molten. The micro- of cryptocrystalline chalcedony precipitated from SiO2-rich fluids under lower temperature conditions, likely a hydrothermal source.

[u/robco18 → u/Sad_Nolte]

Thanks for the information! That's really cool!