Mayan/Aztec necklace Mask?

I bought this old necklace mask from a lady years ago who said her brother was a missionary and traveled into the hills of the Mayan and Aztec tribe,this was given to him,he in turn gave it to her,she didn't like it because of the snake in the middle,there's 2 small holes for hanging around neck I suppose,you can see the crude holes and some wear from wearing against the body,I tried a few people online who said they knew nothing about it,so maybe someone on here can help.There's a broken piece on the side