I'm guessing this is sodalite. Pieces of raw sodalite that I have are darker blue than this but the true color of this piece is darker than shown in the picture. The flash kept washing it out.
The pendant is 1¾ x 2¾ inches. The gold tone frame is convertible from pin/brooch to pendant. It is shown hanging east to west but it has a tiny ring at one end that will allow it to be hung north to south. The pin closure goes east-west. The chain is 19 inches and is easily removed.