Chunk of Mythril

The Chunk of Mythril, named Silver in the original release, is a key item that appears in Final Fantasy Adventure and its remake, Adventures of Mana.

Final Fantasy Adventure/Adventures of Mana
Sumo searches for a way to reach Glaive's Airship after Fuji has been kidnapped by Julius. Unfortunately for him, the only way to get through a rugged terrain is to get into the Gaia Pass, whose entrance houses a sentinent entity called Gaia. The earth spirit spits the hero out upon entering, forcing Sumo to detour to the Dwarf Cave where he learns that the nearby Forbidden Mines houses veins of Mythril Silver deep within. Our hero ventures into the mines, eventually finding an aventurous dwarf named Watts who gladly joins the hero in his quest since he is also in search of the precious metal. The duo eventually reaches the end of the cavern, where they defeat the Megapede guarding the Mythril ore. The savvy dwarf collects the ore and sells Sumo a full set of armor made of the shiny metal. Fully clad in Mythril, the hero can finally continue his quest by entering the Gaia Pass.