The Obsession With Mithril in the Lord of the Rings

Peter Jackson felt the need to up the stakes with the one ring by tying Arwen's life to it. And they seem to doing a similar thing here, saying that the future of the elves is tied to Mithril and it doesn't seem necessary at all to me. So we know that Sauron really liked Mithril. Yeah. It says in the Council of Elrond of what they brought to light, the orcs have gathered nearly all and given it in tribute to Sauron who covered it. Right. Do we know that the other two, we know that Galadriels is made of Mithril, but we're not given that the other 2 are Mithril? No