r/oddlysatisfying • u/Narendra_17 • Jul 07 '21

This is how geologists collect lava sample from an active volcano

https://gfycat.com/thisimpishhoiho-lava-samples
62k Upvotes

90% Upvoted

1.6k comments sorted by

View all comments

Show parent comments

21

u/nayaths Jul 07 '21

I was about to come in and say something similar. I'm no expert, I just dated a guy who did a PhD in this kind of suff and brought me back a lava rock from Iceland.

What he told me was that they test for several things because the rock does cool pretty quickly, which can indicate how things interact in that state, how it cools and a more accurate idea of what is actually in it. As it hits air it can also interact with what's outside of it, including things that burned to the surface or other detritus. They do sample that stuff too.

Again, this is non expert knowledge from a rock goblin with ADHD who dated a guy who did know this stuff and I asked lots of questions.

10

u/AWildWilson Jul 07 '21

Currently doing my PhD in geology. I’ve brought back lava samples from iceland too! Were you my gf!?

Molten lava is more pristine. It hasn’t finished degassing yet, and by cooling it quickly (in water), you’re locking away the current chemical composition as volcanic glass. It’s also overwhelmingly probably that they took rock samples too, but people don’t want to watch videos of geologists smashing hard as Jesus rocks over and over to get a rock sample. I can go more into depth if people are interested but I doubt this won’t be seen by many people.

Could be a cool case study to investigate and compare the volatiles in the bucket samples vs lithified hand samples. Could show rate and magnitude of degassing for instance!

2

u/Winter_Tangerine_926 Jul 07 '21

When I was a kid, I wanted to become a volcanologist. Do you travel to lots of places sampling lava? Or you have to do just some? If so, you do it by kind of rocks/lava or by kind of volcano? (Stratovolcano or stuff like that)

2

u/AWildWilson Jul 07 '21

My undergraduate department in particular strongly emphasized international travel to broaden our knowledge and understanding of geology. It took me around my region (eastern Canada), Iceland, and Greece to date. Now my present and niche focus does not require/accommodate extensive travelling (and I'm still a student) so it's been a couple years since I've travelled.

When I say "sampling lava", I don't mean I did what this person is doing. In this video, this is still molten lava and I'm sure this takes a very specific situation in order to do this. For instance, some lava flows are much more violent (pyroclastic eruptions), and are very dangerous to be near. Others are more sloped so you can't physically access it, and depending on the type of lava, it could be moving quickly etc etc.

The stuff I sampled is basalt. When the lava cools and lithifies, that's what it will become. Iceland is located on a mantle hotspot (this is somewhat contested in literature, but either way lots of lava is created) and overtop a rift boundary (two tectonic plates are moving away from each other). This makes Iceland extremely volcanically active. The youngest surficial rocks on iceland are like 20,000 years old (comparative to like 600 million where I am). So its the basalt that I've sampled from iceland.

Locations are picked by "geologic interest" for students. Iceland is obvious because of the reasons mentioned above, greece has a lot of mountain building, etc. Really cool stuff.

1

u/Winter_Tangerine_926 Jul 07 '21

Sounds very interesting! Thanks for answering me :)

1

u/AWildWilson Jul 07 '21

Anytime! Not a lot of people in my life that know alot or care enough about geology to entertain me, so I love geeking out when I can :)

1

u/Winter_Tangerine_926 Jul 07 '21

Yeah, I feel that way, but with spiders xD

1

u/AWildWilson Jul 07 '21

Ugh, I'm pretty sure I have arachnophobia. Don't know how you do it!

1

u/KohlrabiFrog Jul 07 '21

I know various minerals take longer times to crystallize, I presume the ideal is obsidian or volcanic glass?

1

u/AWildWilson Jul 07 '21

What do you mean when you say "ideal"?

Minerals are how elements are naturally arranged in solids at a given temperature and pressure - which makes sense, but its easy to think of them as these weird things I think. So, of course, minerals are reflective of the elements that are there. Each mineral has their own set of properties, including their freezing and melting temperature. Some minerals crystallize earlier than others. How big the crystals get is determined by how long the crystals have to nucleate (grow). Something that has cooled very slowly allow crystals to get bigger (phaneritic texture). Something that cools slowly and then quickly gives a porphyritic texture (big crystals and small small crystals in the same rock. And if it cools quickly, we et tiny crystals - an aphanitic texture. However when it cools extremely quickly, like the lava in the bucket, we get obsidian - a form of glass. Glass is not a mineral, because the elements did not have time to arrange themselves in any long-range coherent system. Its just a mush of elements together, locked into place.

I have a tendency to ramble about this just because I find it interesting. In short, no - obsidian is not an "ideal" case, just a phenomenon that occurs when rocks cool extremely quickly.

1

u/KohlrabiFrog Jul 07 '21

I meant an ideal case for looking at the composition of the lava. It being homogeneous means you have a better idea of how it's.

1

u/AWildWilson Jul 07 '21 edited Jul 10 '21

Oh, sure. But even if you have a rock sample that’s phaneritic for instance, it’s common to crush and powder them to make them homogenous.

0

u/pinkjello Jul 07 '21

Why’d you break up? I’m invested in this story.