Red Ore is an item from The Legend of Zelda: Oracle of Seasons. It is forged with Blue Ore in order to make Hard Ore, which can in turn be taken along with the Wooden Shield to the Subrosian Smithy to create an Iron Shield.
Red Ore can be found in the house west of the Sign-Loving Subrosian. The house can be accessed by using the Magnetic Gloves on the pedestal near the entrance of the house to pull Link over. Link will find the Red Ore on the roof of the house.