Item:Soul Gem: Essence of Earth

Can be obtained by casting Trap the Soul spell on a CR7 Earth Elemental and used for Adamantine Ritual. You must use Small Khyber Dragonshards and HD 20 version of Trap the Soul spell for CR7 Earth Elementals. Note: CR8+ Earth Elementals are too high, and will result in a Strong Soul gem (unsuitable for the ritual).

Quests with CR7 Earth Elementals:
 * Two in Halls of Shan-To-Kor (Elite)
 * Two in Caverns of Shaagh (Hard)
 * Four in The Depths of Despair (Elite)
 * Four in The Depths of Discord (Hard)
 * Five in The Forgotten Caverns (Hard)
 * Eighteen in Taming the Flames (Hard)
 * You can find an infinite number of Earth Elementals in The Lord of Eyes (Normal). Go to the collection room and use Trap the Soul away from the center platform.  Normal gives the correct Soul Gem.