Depleted Crystal Focus

Source
This item can be looted from
 * Aether Rays
 * Apexis Flayers
 * Shard-Hide Boars
 * most other level 70-72 mobs on the plateaus.

They are not Bind on Pickup and can be traded to other players. However, once converted into a Charged Crystal Focus, they become Soulbound.

The drop rate is about 2.5%.