Hi @kgirl,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Unfortunately, to limit the damage to the flooring beneath, a hammer and chisel are likely your best option.
You could try using a Carinya 1.2m x 150mm Floor Scraper, ensuring you run it along the line of the floorboards, not across them. If you were to use this method, I would suggest wearing long protective clothing, gloves and eye protection as there is some potential that the slate will break and become airborne.
You could also use a rotary hammer drill on the non-rotation hammer function with a chisel bit. Once again, you would want to go with the floorboards, not across them and ensure you wear your protective equipment.
With either of these methods, you need to ensure you keep the tool at an acute angle to the floorboards so that it doesn't dig in and damage the floorboards.
Let me know what you think and if you have any further questions, please don't hesitate to ask.
Jacob
