Countertop components fabricated out of granite and other natural stones are sometimes reinforced with metal rods inserted into grooves cut into the underside of the stone, and bonded in place with various resins.  This procedure is called "rodding" by countertop fabricators.  Most commonly, these rods will be placed near sink cutouts to prevent cracking of the brittle stone countertop during transportation and installation.  Data published by the Marble Institute of America shows that this technique results in a 600% increase in the deflection strength of the component.
However, if a metal rod subject to oxidation or other forms of corrosion is used, and moisture from a sink or faucet reaches the rod, oxide jacking can crack the countertop directly above the rod. Mild steel and some grades of aluminium rods are known to cause oxide jacking failures in granite countertops.  Skilled stone repair professionals can disassemble the cracked stone, remove the metal rod, and reassemble the stone using various resins tinted to match the colors of the stone.  This type of problem can be prevented by using reinforcing rods made of stainless steel or fiberglass in the rodding procedure.