I don't remember where each one is at exactly but..
One is hanging in a cage above the runes
One is at the top of a ramp in the main room, ramp visible only with helmet on
One appears on a desk after solving the 4 pressure plate thing, one plate being visible only with the helmet on
One appears on the podium-alter after you match the colored flame torches with their invisible counterparts, visible only with the helmet on
One appears in the room with all the beds, accessible only after entering the corner room (walls vanish with helmet on) and pulling the lever which creates platforms to jump up to the orb.
