Polished Slate Stone White Zig Zag Rounded Triangle Earrings

Polished Slate Stone White Zig Zag Rounded Triangle Earrings. In good preowned condition. No markings or brands. No precious metals. Silver tone hook clasp. I cannot 100% identify what stone this is but it feels like slate and is cold to the touch. White zig zag pattern on the fronts. Measures 1.5 inches long