Taking clay from natural soils requires mixing with water, settling, separation. Or crushing and dry separation, to get the fine enough particles that have the properties you want or need. And usually a degree of experimentation and learning to find the right sizes and properties that give different ultimate results. And some luck and experience in finding soils to start with.
Nice job! I like what you did. The only addition I would make is to add a bit of color. The introduction was beautiful. I know it was a lot of work to make the animations and frames by hand drawings. Not sure of your plans. But silicates (sands) when fired become glasses. Now opaque ceramics often have transparent and often colored glazes. Have you ever experimented with find particles that are both? Clays with enough glass starting materials that when fired they are semitransparent? Just visualizing the materials and processes, and it occurred to me there are many streams where sand and clay are deposited close to each other. When does the opaque clay material and the glass sandy material overlap or mix? Just a thought, but I have memorized many microscopic views of sand and clays and the “clay” particles are mixed in with “sand” particles.
I find pure transparent glass and plastics and acrylic to be OK for some ideas. But where you can see the intricacies and patterns of flow in semitransparent glass are most intriguing. Pure silicon dioxide (quartz particles) need things like sodium carbonate (“washing soda”) and calcium carbonate (limestone) to lower the melting point and start the fusion of particles. I am not an expert on glass. I have never made it. I am just remembering my reading. And broken glass is already made and can be mixed with clays. Wish I could give you better pictures, I cannot draw that well and I can only give you words or links to pictures.