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.