Elunite Ore is a quest object for the Alliance Warrior quest . The ore can't be used by Miners or Blacksmiths for any of their crafted items. Elunite ore is a fine metal to work with, for it is considered to be blessed by the goddess Elune herself.
To find the shipwreck, go to the end of the dock near the lighthouse and then head south through the water. You should eventually see the shipwreck.