Green Glass Oil Lamp

I've been collecting oil lamps for some time now - but usually just the cheap tin and brass-plated type. More recently I've been refining my collection with better quality authentic lamps.

This one was purchased at a garage sale for $4 because I liked the green glass; it's a good match for the green glass butter dish I've also posted from my collection. This lamp has quite a bit of weight to it and is quite large at 19" tall and nearly 6" wide.

The glass has lots of bubbles and looks fabulous when the sun shines on it. Based on the seam running down the middle I'm guessing these are made via a casting process?

I just buy these when the price is right and if I like the look of them and don't know anything about their age or origin. Maybe it'll have a similar surprising value as the green butter dish?!