This is a wonderful oil lamp made sometime between 1860 and 1915. It was originally clear and has been irradiated to make the exquisite purple color. The base is 9"tall and with the burner and chimney it is 18 1/2" tall.
Purple Oil Lamp
Originally lead was added to glass to make it clearer. After the civil war there was a shortage of lead so maganese dioxide was added to the glass instead. This happened from approximately 1860 to 1910. It was discovered that exposure to sunlight caused this glass to turn a light purple. In the 70's someone figuired out that exposure to UV lights or xrays created a more intense color in a faster amount of time. The more maganese the richer the color. These pieces are referred to as Irradiated Glass, or Sun Glass or Desert Glass.