Marble is too soft. Granite is better. I've made arrangements for my most important personal data (full name, birth and death dates) to be engraved on a granite slab when I die. This slab will be physically arranged alongside others, one for each family member, showing the relationships among people. This will be set up in a special location set aside for that purpose, outdoors safe from fire and building collapse. I expect the data to still be readable hundreds of years from now.