What 'rocks/minerals'' are safe for Aquariums? I want to engrave an Ancient Greek inscription for tank (Interesting thread!)

[Mentat]

... I need help with the slate upon which I will write/carve the text. This material in question needs to be safe and clean for my aquarium. I was hoping that I would find help here on that particular issue.

I would go to nearest funerary and talk to person in charge of carved headstones. Think they could get you a thinner (headstones are thick and heavy) piece of granite or marble and carve it for you, or just sell you the stone and you can carve it yourself. Good luck !