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An E40 socket is what is used for the large CFL's and HID bulbs but the way to tell is what type of plug end you have.
For a CFL you will have a plug that fits a normal power outlet but for any HID setup you will have a plug that will fit into a ballast...usually this has a round pin or pins. Your photo looks like round pins so I'd say you need a ballast and a HID bulb.
Disclaimer: I'm in New Zealand and were you are from might have different plug configurations but the plug end is the clue either way.
The e39/40 was really thought up for HID's which explains the ceramic material. Later retrofit lamps appeared in the shape of not so compact florescent. Which became popular enough that people made shades with them specifically in mind. Which yours looks like, with that plug. It's an early one though, as most now have a plastic lamp holder. Plus the sticker to say no HID's allowed.
Meanwhile, in the real world of lighting, LED retrofits have arrived. Same E39/40 lamp holder requirement, but designed to replace HID lamps effectively. You would never relamp a warehouse with them big fluorescent things, but the LED variants are the real deal.
I would probably bin it. It's perhaps useful as an occasional light, but a 50w LED flood is about $15 and a lot smaller.