Mithril

Mithril is not a fantasy metal. It's bronze from the Middle Bronze Age. The first bronze was arsenical bronze, made from a single ore. It's stainless, and does not include tin. Mithril is arsenical bronze with antimony. Antimony makes it harder than tempered steel, arsenic makes it stainless. Weapons and tools were made with both: tough bronze with moderate arsenic and no antimony; the cutting edge is hard bronze with antimony and lots of arsenic. The colour in this mod is taken from a real bell made with this metal. It's stronger than iron, but less than diamond.

Smelting anything with arsenic will produce toxic gas. Breathing that gas will cause poison, like Cave Spider poison. Eating garlic causes the human body to expel arsenic 45% faster, so this mod adds garlic and eating garlic instantly cures poison. It doesn't clear beneficial potions, just poison.

More on the Forge forum: http://www.minecraftforum.net/topic/1581930-rbdycks-mods/