A bit of research about gas lanterns and their reflectors, seem to indicate that many are brass in construction, however; I have found a few lesser quality models , or knockoffs, that have aluminum reflectors. Below is one example of a hand held lantern,..note the reflector....Greg's suggestion that what Mr Spink found and what the last Niku trip discovered, that being, they may be reflectors of some type, seems a good suggestion. As for the holes in the outer edges of the Spink artifact , ....it is my thought that possibly some sort of shield may have been attached, possibly due to the hazards involved in handling such an instrument. It is easy to see how this reflector could become detached from the parent object, and leaving none of that to find, if it came from one similar to the one below. There seems to be some flexibility in and around the inner hole, to allow cycling, to create some of the creases and damage noted on all three artifacts, as well as signs of solder or brazing work to hold the object to another piece.