Ignotumite is a super rare mineral found deep within the overworld. It has limited uses, but has infinite durability

The ore yields off a humming noise, is mined with mithril or better and drops ore as an item (blocks can be smelted to ores if used with silk touch)

Ignotumite has a 3 stage process:
First off, hammer the ore item into dust with an anvil or trip hammer
Put the dust in a blast furnace. this creates an impure ingot
Alloy the ingot in a granite crubible with 4 flux (Ratio 1:4)