Ancient Ingots

The rare ingots can be found by being an archeologist and digging for them, they are very rare and have a 1 in 800 chance to be in an archeological dig site. The ingots have a variety of purposes, They can be used just like any other iron ingot, but the tools they result in are more durable then diamond, maybe 1.5 times or so. They can also be used to create a special type of iron golem, which has more health then the average one, and can be assigned to guard certain places from certain mobs and players. (Ex. The Golem will allow any other mob in except creepers, which the golem will destroy if they get into a certain radius.) They can be healed with iron ingots.

Shears will also be different, they will have no durability limit and go twice as fast as normal shears. When used to harvest wool, the sheep will drop more wool as if the shears had a fortune enchantment. a bucket would be able to hold twice the liquid normal, but if the bucket has two different liquids in it at the same time (ex, lava + water) the bucket breaks. 

Shields can deflect fireballs back at ghasts, but otherwise do nothing different, Crossbows will have the same durability increase and shoot arrows faster. Flint and steel will produce a blue fire, and nether portals can be lit with the same iron blocks instead of only obsidian

The Ingot and all block appearances would be a dark blue (when not in use / in inventory) or glowing blue (When placed or in use)