@doctorrevelator answered the question much better than I could. Finding a good supply of 'sharp sand' as I call it in my work as a sand sculptor can be quite difficult. I use this same kind of sand as they discuss in this ICO When there was a building boom in Ireland the quarries were bought up for construction and they refused to sell me any for my work. I believe that in the future it will become a finite resource and this coin could be a good investment and the beginning of crypto in many other resources. Imagine water coin. Sand In Ireland now costs about $50 a cubic meter.