Vintage valve for gas lighting, the way we lit our homes before the turn of the century...the last century.
Many forms of lighting did not have threads on the other side where the gas comes out.
Here is one I found, common is that graduated nozzle end to attach to the fixture like we used to have back in chemistry class where a Bunsen burner rubber tube should be attached.
Others, like the fixture in the table torch lamp below, had straight pipes connected into that end instead.
This is what yours is, although made for a much smaller lamp.
Heavy, throw it in a tumbler and it will clean up nicely.