Fixing a marble fire surround

[peterb]

I want to fix a 2nd hand marble fire surround to a breezeblock / plaster wall. what is the best adhesive to use? It looks as though it was originallty fixed with silicone ...I'm not sure this is sufficient. Would you recommend using fixing brackets of some form? Will the hearth need to be cemented to the wooden floorboards or can it just rest on them?

many thanks for any help you can give me