闇の石 [yami no ishi] or 'dark stone' in Japanese.
Final Fantasy XII
Buy: - (sell: 35 gil)
Use: Blood Sword, Capella & Silent Shot, Leather Headgear & Leather Breastplate, Shortbow & Parallel Arrows
Drop: Dark Elemental, Dark Skeleton, Ghost, Lich, Lost Soul, Skeleton, Skull Defender, Skull Warrior, Specter, Zombie, Zombie Mage
Steal: Dark Skeleton, Hell Wyrm, Lich, Lost Soul, Oversoul, Skull Warrior, Specter, Zombie, Zombie Mage
Description: A stone infused with a dark power. It looks like an ordinary stone, yet casts and eerily twisted shadow.
Grimoire of the Rift

Buy: - (sell: 600 gil)
Use: Apocalypse, Black Quena, Blood Sword, Energy Mace, Hades Bow, Poison Knuickles, Silver Cannon, Thief's Cap, Bone Plate
Reward: Wayward Drake x5 (once), One-eyed Evil x3 (wandering monster)
Type: Magicite, Rank: ★
Description: A stone imbued with dark magicks. The black blotches covering it are disturbing to behold.
Final Fantasy Tactics S

Buy: - (sell: 50 gil)
Use: Dark Ring
Obtain: Western Orda Woodsea/Devils' District
Description: A somewhat uncommon piece of magicite
Category: Item