The Arkenstone of Thrain
Provides resistance to light, dark. Cannot be harmed by acid, electricity, fire, cold. Sustains your life force. Grants the ability to see invisible things.
When activated, it detects treasure, traps, doors, stairs, and all creatur es nearby. Takes 31 to 60 turns to recharge.
Radius 3 light.
Min Level 50, Max Level 127, Generation chance 2, 0.5 lbs

(Angband 3.1.2v2)