2 sandstone veins came back. The first one i erupt and freez and than mine it away. It came back the next day, i already reinforced the floor and put cateyes on it. The cateyes were not activ. The sandsone just grow over them. Than a other sandsone erupt and freez but this time i was thinking i dont mine it away i go first erupt all the others, 2 days later it become a sandstone vein. In the mean time i have make the cateyes green at the first sanstone location. after i erupt and freez it again. I hope this works for me.