When I was about 4, I had heard of the ‘water cycle’ - you know, water on the ground evaporates and becomes clouds, then rain, then it’s water on the ground again. I also knew about ice (I lived in Tucson, AZ).
I figured that when the water got really tired, it turned into ice, and then into clear rocks, and then gradually got dirtier and dirtier. So quartz was ‘young, relatively clean’ rocks, while most pebbles were ‘old, dirty rocks’. When the rocks got crushed, they turned into gravel, which eventually got worn down into sand, which turned into dust. When the pieces got too small to see separately, they were water again and back to the ‘water cycle’ mentioned above.
I even had a piece of ‘new rock’ that proved this theory. It was probably just a very worn piece of glass.