Clean travertine and copper stains?

Have a job to possibly clean this travertine. Most isn’t very dirty but one area has according to the client copper staining from copper gutters (I only saw painted or maybe dark copper gutters?

Never cleaner travertine before.
Also needs some flagstone steps cleaned and the drainage goes right down onto the travertine area.

Not totally sure I want this due to poor drainage but looking for thoughts on what’s used on travertine and for the copper staining?
She said last company used vinegar for the stain.



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