It is a "Shriners" (fraternal organization) lapel-pin. The Shriners organization was first established in 1870, so your lapel-pin is from sometime after the civil war. The screw-pin on its back indicates it is from the early 20th-Century. Shriners - Wikipedia, the free encyclopedia
I recognized it immediately by the Shriner's famously distinctive logo showing an Arabian sword above a crescent. I do not know the meaning of what appears to be a horse or mule or cow's head on your lapel-pin. It may represent a particular "temple" (the Shriners' name for a local club), or rank. Under super-magnification, I see it has some writing on the crescent. Please do your best to tell us what that writing says. Perhaps somebody here has the spare time to research it, but I can't do it, because my wife has plans for me tonight.
