Hi @colinweiren
Wow thats a nasty break
To Glue it i would use super strength araldite
I would use clear packing tape over the glue on top side of the table to give a flatter glue finish. underneath optional.
You will need to sand any table top glue lumps off with a sander using wet and dry sand paper 1200gt There may be hollows you will need to fill with glue and sand again until the table top looks lovely flat and polished the clear glue will blend in and the join will look like a marble natural feature
But I would recommend if possible structural supports under and across the crack line if possible
I might be tempted to glue a Ply board smaller than the marble cut to shape and use it to support both halves.
To Save money I might use super strength builders glue in the bottom half of the crack and also to glue support tubes on with and only use araldite in the top 5 mm where it needs to be clear. Use glues at the same time.
Well big job ahead if you love this table.
But doable.
