I would have carefully cleaned the rough soil of with destilled water and a cottonstick and dried it very fast. 
The clay sized soil in the moulds i would have left since it would be very hard to remove without damaging the surface. 
 
Storage: I would have used hydrophil silicon beads combined with a food safe bag. 
 
 
Ps: I am no metal expert
		 
		
		
		
		
		
		
		
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