Hi @diego01,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Burn marks on stone benchtops can be a bit tricky and it is fairly likely you'll need to employ the services of a stone benchtop repair company.
I'd suggest you start by mixing baking soda and water to make a thick paste. Apply the paste to the stain and let it sit for a couple of hours or overnight. After the wait, wipe it off with a soft, damp cloth.
If this doesn't work, I'd suggest contacting a stone benchtop repairer for assistance.
Let me know if you have any further questions.
Jacob
