Slate

Transcript:

Sarah: This is your mountain camp, but now in your mountain camp, all around kind of the top of this mountain you have some slate. 

Kim: Oh, okay. 

Sarah: Yeah so the slate looks a lot like the shale, and I wonder if you wanted to talk about, is there a connection between them? 

Kim: They're very related. So, again, they're buried clay or mud size material that is being formed together into a rock, but slate is just it's a little bit more fissile, so it likes to split apart. very these very fine layers give it some structure that likes to split apart.

Sarah: Now this thing on the wall that you can write on with what looks like chalk is also called a slate. 

Kim: Oooh, I like that. 

Sarah: And I know that our shale is sedimentary, but we are now in the metamorphic part of our world. 

Kim: Oh that's a really good point so yes so slate is a fine-grained mud rock, so it like it's very fissile, it likes to break apart into layers, and since it breaks into these layers, they usually used it as a writing surface, so instead of having loose leaf paper we didn't have that option a long long time ago for school, so they used to write on slate. But, yes, it is something that has been heated up a little bit further, so it's no longer a sedimentary rock anymore, it is a metamorphic rock. 

Sarah: So I know that when we talk about biology, metamorphosis means transformation, like a caterpillar into a butterfly. So is that like a transformation from shale into slate?

Kim: That's right so that's just the same idea. So with rocks, how we change them is through heat and through pressure, so the rocks do change some of their properties, sometimes it changes the minerals that are inside them, and that is the type of change that we see, not into beautiful butterflies, but into beautiful different rocks that we see.