Bridge Lamp

I know very little about this lamp. It was in my sister's home when she moved. She was downsizing and no longer wanted it. I have admired it for such a long time and have always been intrigued by it so she gave it to me.

After some research, I believe it is made of cast iron. It is certainly heavy enough!

I've done nothing to clean or shine it because I don't wish to do damage. I have been using a plain old Walmart lampshade for it.

Would love cleaning tips as well as suggestions for an appropriate lamp shade.