Answer:
A certain wizard resided in a city made from this gemstone.
I am the heart that does not beat. If cut, I bleed without blood. I can fly, but have no wings. I can float, but have no fins. I can sing, but have no mouth.
Only two backbones and thousands of ribs.
I can ruin your day, or darken your life. And while I'm expected, I'm never alright. I'm bad for business, and worse for your hair. Wherever I am, there's something not there.
What is a five-letter word that has brain in it?
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.