Ubatuba Granite. Chip on Surface. Caused by Metal Rod
In order to strengthen a weak part of counter top a stone fabricators use a metal rods/bars for purpose to strengthen a weak part of counter, in most cases it’s around sink cutout or narrow and long backsplash. Also it can be useful in weak kind of stone (with lot of internal/hidden cracks or veins) or just poor quality stone. Fabricators make a channel in stone body from back side, then fill up it with liquid epoxy, then insert into a metal bar.
In years with contact with water a metal can start rusting and expanding in volume, so it can lead a counter to be cracked or chipped as on picture below.