Baldur's Gate : The Sword Coast Chronicles : NWN2 Persistent World

I been wondering why do we no get gems from the crystal cave we have some caves where we can mining but now the Nashkel mine close we could add so we get gems from that crystal cave we can Mining in the Troll Mine we have Mineing in some caves on the Land Ho caves i think there more but could we add some mining in the Crystal Cave at the Nashkel Mine?

could we get mining in Underdark caves there some areas has huge crystals but no why to mining them as on surface?