#Aang is having a lot of fun. Sokka on the other hand is Observing and very close to discovering the atom.
I had to go dig this up because I just spent an hour and half (closer to two hours now) trying to figure out how Earth bending works. Because rocks are made of minerals, and earth as in dirt is also mostly minerals, and crystals are, you guessed it, also minerals.
Now, water bending establishes more than any other element that you can absolutely bend things that only have components of your element in them. Most notably blood bending, but there's also the plant benders out in the swamps, and Hana teaches Katara the slightly less horrifying skill of drawing water from the air itself if it's humid enough. While blood is 90-ish% water it's still not actually water by itself, it's a mixture. It's actually kind of a more disturbing version of watching water benders work with mud (something that seems to be a joint domain between water and earth).
Now this is all well and good, and the idea of bending part of something to move the whole is further established by metal bending. Toph is able to bend impure metals by latching onto the earth within them. This is also the explanation given for why you can't bend platinum or other pure metals, there's no earth for her bending to use.
But here's the thing. Metal is also minerals. Iron is a mineral. There are crystals made of metals. There is absolutely no reason earth bending shouldn't work on an iron deposit you yoinked out of the ground unless you just decide that earth bending just doesn't like metals.
But it gets worse because by the time I came to this conclusion I had already spent far far far to long trying to figure out what rocks, minerals, crystals, metals, metalloids, ect are and are not. Water is H2O. Water is simple. For rocks and crystals, it seems like the structure is really important, but unfortunately lava bending is just kind of chilling in the corner ruling out that hypothesis as well.
There has to be some kind of definition for what is and is not earth when it comes to earth bending (Watsonian not Doylist, we are well past Doylist) but it's not "made of minerals" and it's also not "has a rock structure." So is it really just minerals at any temperature that are non-organic but also non-metalic? Metal bending shows you don't need something to be all earth, or even mostly earth, in order for it to be moved by earth bending. So what percentage of a thing needs to be earth? Why don't metals count? There's even an episode in the show where Toph bends an asteroid, showing that earth doesn't even need to come from Earth. It raises so many more questions.
Worst of all, naturally forming snowflakes aka crystals, by some definitions, make ice a mineral. Which is so clearly not something earth benders should be able to bend.
And anyway at no point during my research did I actually narrow down what counts as earth for earth bending, but I do feel like this is the kind of thing that would send Sokka into a spiral for an episode the same way it sent me.