I found this Zippo lighter while cleaning out an old desk drawer; it presumably is a family heirloom but has no sentimental value for me. But before disposing of it I thought I'd inquire about that logo on the side.I presume it's the 15th anniversary of something. The lighter would have been used by my father in the 1950s-60s, and it likely was given to him by a customer or friend, since he didn't spend money on fancy Zippos.
Does the logo look familiar to anyone?
Addendum: a tip of the hat to reader Gelvan Tullibole 3rd, who found the logo (in Wikipedia no less) associated with NL Industries.