Since dust and marble are terrain things, I feel like having a prime that lets you place them would be too strong. I could see a prime that specifically lets you place its own dust or marble (and then said marble effect would reflect this). Given that dust and marble work for any number, something that lets you manipulate them as a whole should be "above" the system of primes, so I feel that something like "choose a stone of yours on the board, it's crushed into dust or marble" would need to be a lab item, not a prime effect.