Vintage Abalone Alpaca Mexico Brooch

Beautiful old abalone shell brooch crafted in Mexico in “Alpaca” metal, which is an alloy of copper, nickel and zinc. I am unsure about the black material, but it is semi-glossy, and probably acrylic. The curvilinear design is especially lovely, and makes me think of the sea shore. This piece is in excellent vintage condition, and measures 2.25” x 1.25”