A Link Between Worlds: Master Ore Locations
In A Link Between Worlds you get the chance to upgrade the Master Sword twice so there are 3 different versions. 1. Standard silver blade, 2. (Tempered Sword) Red blade and then the strongest 3. (Tempered Sword) Golden blade. However you will need to find 2 pieces of Master Ore per upgrade giving a total of 4.
below i will list the location of where to find those pieces and the requirements you need to complete the task. One thing i will say is these can be done any order the list is no more than a location guide and the order in wich I played through.
Location: Thieves' Hideout
After finding the Thief Girl and escorting her out of the dungeon, you'll come across a room in the Basement filled with water. At the southwest corner of this room, there are a pair of floor switches. Step on one switch and have the thief girl step on the water, causing the nearby wall to open. Run down the long hallway and open the treasure chest to get the Master Ore. There is also a red rupee trail leading to the chest.
Location: Skull Woods
The Master Ore is found in one of the final rooms of the dungeon where Link needs to get the two Eyeballs. One of the eyeballs can be found on the higher ledge at the south end of the room. There is a large treasure chest just north of the eyeball. Link can merge along the wall to reach the treasure chest that contains the Master Ore.
Location: Dark Palace
On the 2nd floor of the Dark Palace, there is a room with six windows where light shines in. Just north of this room there is a small rectangular room that has a treasure chest. In order to reach this room, first be sure the platforms in the center of the room are lowered. There are two switches, and while both activate the platforms, the lower switch also causes the wall to the north to flip when it is hit.
Place a bomb next to the bottom switch and then quickly run northward to the platform above. Strike the nearby switch to get to the higher ledge and run to the northern wall. Once the bomb explodes and hits the southern switch, the wall will flip, causing Link to enter the small rectangular room. Open the treasure chest to get the Master Ore.
Location: Philosopher's Cave
Requirements: Titan's Mitt
Go to the Sanctuary in Hyrule and use the crack to enter Lorule. Exit to the south and walk eastward to the graveyard. At the northeast corner of the graveyard, use the Titan's Mitt to lift the large boulder and head down the steps.
Press the switch found at the west side of this cave and go through the door that opens. Make your way to the northwest part of the room and climb the steps. Walk along the path to the right until you reach a treasure chest. Merge along the wall to the east and walk on over to the small key. Use the locked on the locked door to the northwest.
Defeat the three red Eyegores that appear and then head up to the next room. Pull the switch on the right and then head up the staircase.
Merge along the wall to the right to reach the large treasure chest and open it to get the Master Ore.
At the start like I said these can be done in any order and was just the way I chose to go, so feel free to explore both Hyrule and Lorule as you see fit. I hope this go's some way in helping any of you that are still searching. Enjoy