Schwarzstahl

Schwarzstahl is a special type of steel which was developed by Jacques Piazzini, the father of Tendokyo Thirteen's scientist Francesco Piazzini. Schwarzstahl is used mostly in New World weaponry and used only in small amounts due to its rarity. Due to its immense strength and durability, Schwarzstahl is said to be the metallic version of the Adam Wood and it was then sold to a very high price at around 150,000,000.

History
Thirty year ago at a secret facility in the New World, Jacques accidentally hit a yellowish gold-colored chemical in a sheet of metal. The sheet of metal turned black and the metal also sparkled. He used a gun to test the hardness of the sheet of metal and the bullet just got stuck in the metal without dealing any damage to it. Further testing continued, using bombs, cannons, artillery shells, electric bullets and still the same sheet of metal continued to seem undamaged. The chemical that accidentally hit the metal was named SWZ, a natural substance, and the metal was named Schwarzstahl. Jacques introduced the product to the Underworld market to make competition with the greatest products of that time, including devil fruits and chemical weapons owned by Caesar Clown.

During the three-year timeskip which happened more than 30 years after the discovery of the product, Jacques' son Francesco did the same. He bought a large amount of SWZ which costs relatively lower than the resulting product. He applied a glass full of SWZ on a piece of aluminum roofing. The piece of aluminum became black and sparkled like it was when it was first discovered. Francesco tested the metal's durability and the result is the same. After this time passed by, Francesco introduced to Kwaito III this new product he discovered and he recommends that this metal will be the main material for the Steamboat Willie.

Trivia

 * "Schwarz" (pronounced Shvarz) is the German word for the color black (no racist pun intended) while "Stahl" is the German term for steel, suggesting it is a type of metal.