The Tears of Poseidon - Scott C. Viguié - Bog

Charles "Tex" Ravencroft, archaeologist and adventurer, has run across a lot of strange things in his time, but nothing could have prepared him for a discovery he makes on a remote island in the Pacific. A single, tear-shaped gemstone made out of a material that's not supposed to exist catapults him into the middle of one of the greatest mysteries of all time. Legend holds that three such gemstones can unlock the location of a city lost thousands of years ago. Yet even as he searches for answers there are those who will stop at nothing to keep the secret buried forever.