Vintage Sterling Silver White Buffalo Black Onyx Pendant w 925 Chain Modernist- Native American Unusual Abstract

This is a very unusual Pendant/necklace it has a good size white buffalo cabochon as well as a black onyx Gemstone, the shape is abstract and I honestly have no idea if this is a mid century modern Modernist Piece or Native American it is signed on the back by the artist but I cannot make it out. The pendant is solid sterling silver tested and guaranteed. Please see photos for approximate measurements and further details. This comes with a Sterling silver chain.