Note and question: look at your pic again.. ask yourself what is in focus.. Now, alter the way you take the pic.. so that the stone is in focus and not the door jam..
Still inconclusive.. and again.. The Quarter is in focus.. and not to harp on you about this. It takes tiem to find the distance needed to get great or even good shots. Although areas of the stone are clear, I (we) can't make out what the shinny materal is.. thou Could be mica..