Stone slab - Best fixing option

[Kabous]

I want to lay a 600mm x 600mm solid/ one piece stone or slate paving slab outside on to a concrete slab.

Which will be the best option and how would I fix it on to the smooth concrete slab?

Any issues that I need to consider i.e weathering, sealing etc?

As always comments and suggestions greatly appreciated.

[Geewizz]

For the small quantity you would require, your easiest option would be to pick up a bag of premix mortar and add water.
How smooth is the slab you are laying on? If it is polished concrete then you might need to rough up the surface a bit for the mortar to adhere. I would make a few cuts across it with an angle grinder.