Pumice

Transcript:

Sarah: So, while we are in this cave, there's actually another rock in here, and this is one that you will not find in Minecraft, this is one that we had to make, so it's a ROM exclusive one. So we've actually got some pumice in here as well, and one of the things that I wanted to demonstrate for you. So I'm going to pick up some tuff, and I'm going to pick up some pumice, and if I put the tuff down and break it, we get that sound. I put the pumice down and break it...

Kim: Oh, it sounds more like glass, that is exciting.

Sarah: And if I look through the pumice that this person is holding, it's ever-so-slightly see-through. You can see the eyes kind of peeking through there. I see it. 

Kim: Oh, that's really, really smart. So, yes, so pumice is related to tuff, but pumice actually has more air in it. So sometimes it's used as an abrasion tool because it's it's a very glassy and crystalline material with just a lot of bubbles in it, so it's very soft, very airy, it actually floats on water if you were to put it into water because there's so much air and so many void spaces in the rock. 

Sarah: That is one of the coolest things and it's one of the things that I wasn't quite able to replicate, my Minecraft skills are not that good but I love that so, maybe when our friends build their museums, they might include a pumice display and figure out a way to have their pumice floating on water to show people that cool property of it.

Kim: I think that's a great idea. 

Sarah: So that is really neat. And then I just wanted to kind of -- over here, we've got the obsidian, and I know with the piece of pumice that I use when I'm talking to our friends in virtual visits, there are surfaces on that pumice that look almost like obsidian. So is there a connection, kind of like a relationship, between obsidian and pumice? 

Kim: There absolutely is. So these are all volcanic rocks, but obsidian is just like glass. This is something that has either come to the surface and cooled so fast that it didn't even have a chance to crystallize into a rock, or, a lot of times, it hits the ocean water, it's so cold, it just has to crystallize. It's almost like a bottle, you know if you have a glass bottle, it's very very glass-like just like that, and actually some of the same processes are used to make glass bottles and glassware.