Many times on the treasure coast this conglomerate is picked up and mistaken for 1715 material....one site in particular yeilds this type of conglomerate. Over several debates about this material ( one of which was on this site) it has been determined that the likely source was a home/condo that had terrazzo floors. The terrazzo in the past came in many different colors, but the green terrazzo was present very close to a popular treasurecoast 1715 beach. This material has been seen and discussed before. I can't say for certainty that your material is this, but it looks the same. I belive the previous material was recovered in the ft. Pierce area....but I can't trust my memory to be certain about that....its definitely not emeralds....there is a thread somewhere on this site discussing this same material. Time and surf has eroded the softer material between the green chips in question....hopefully im wrong and your piece is connected to the 1715 fleet, but I fear you have some ordinary terrazzo flooring !!