@Verbose  

 
I want to say I recall learning about the subject before High School even. Like middle or elementary school science class (and the Magic Schoolbus video games). But I think there-in lies the problem: people like myself learn about it at such a young age and then do nothing with it for so long that we basically forget it or it gets muddled with newer information.

@redweasel
 
Yep, 40%-65%

doesn’t obsidian also have to be high in silicon?

@Tervicz  
Minecraft Obsidian forms at any level where water runs over standing pools of lava, including naturally occurring surface patches.

At level 10 or below…

@Background Pony #1658
 
There are three general types of rocks in terms of formation: sedimentary, igneous, and metamorphic.
 
Sedimentary are rocks that form from other minerals that were broken down. That’s usually done through pressure and time. Less so heat. Shale. Limestone.
 
Igneous rocks form from magma or lava that cools and hardens. You can think of it like ice. The solid point of water is just really low compared to rocks. Obsidian is an example, iirc.
 
Metamorphic rocks are rocks that undergo change through a combination of heat and pressure. They become “plastic” and malleable but are under such pressure, they change shape and structure without becoming magma liquid.
 
So Maud is probably talking about some igneous rock.

How about a description for those of us without a Doctorate in geology?!

<3 Maud everytime she shows up and every moment she speaks!

>lava cooled fast
 
u mean obsidian?

Oh Maud. X3c

Actually:  
 
It’s not even close to what she said!

So mushy shapes, but actually solid, okay.