the lord of the rings - What does Sauron need with mithril?

In The Fellowship of the Ring, Book Two, IV A Journey in the Dark, Gandalf explains:

The wealth of Moria was not in gold and jewels, the toys of the Dwarves; nor in iron, their servant. Such things they found here, it is true, especially iron; but they did not need to delve for them: all things that they desired they could obtain in traffic. For here alone in the world was found Moria-silver, or true-silver as some have called it: mithril is the Elvish name. The Dwarves have a name which they do not tell. Its worth was ten times that of gold, and now it is beyond price; for little is left above ground, and even the Orcs dare not delve here for it. The lodes lead away north towards Caradhras, and down to darkness. The Dwarves tell no tale; but even as mithril was the foundation of their wealth, so also it was their destruction: they delved too greedily and too deep, and disturbed that from which they fled, Durin’s Bane. Of what they brought to light the Orcs have gathered nearly all, and given it in tribute to Sauron, who covets it.

Why did Sauron desire mithril? What did he use it for?

Answer

Presumably for weapon-making

In an early draft of Fellowship, Tolkien wrote a margin note saying:

Mithril is now nearly all lost. Orcs plunder it and pay tribute to Sauron who is collecting it - we don't know why - for some secret purpose of his weapons not for beauty.

^{History of Middle-earth 7 The Treason of Isengard Chapter IX: "The Mines of Moria (1): The Lord of Moria"}

And Christopher Tolkien remarks in a note:

Another draft puts this slightly more fully: 'They give it in tribute to Sauron, who has long been gathering and hoarding all that he can find. It is not known why: not for beauty, but for some secret purpose in the making of weapons of war.'

^{History of Middle-earth 7 The Treason of Isengard Chapter IX: "The Mines of Moria (1): The Lord of Moria"}

But we don't see Sauron's armies using any mithril weapons, so we don't know what he actually ended up doing with it. As far as we know, he just stored it in a giant warehouse near Barad-dûr for his "personal use".