Antique mosaic button, rectangular shape. I believe this is black glass(?), molded all in one piece with a stud type shank. Decorated with a tiny mosaic image of a dog. (The mosaic shows up better in the 3rd photo, taken with flash.) Condition is vintage with chips to the top right hand corner at the front, and chips to the stud shank on the back. Despite wear, still a charming and rare little dog button

Size 9/16” (1.4 cm) long