What is the Eye of Sauron?

[Gordis]

Hi, everybody,
I have a question for you. I am not aware of its being discussed before.

WHAT is the eye of Sauron?
I don't mean the physical feature of his body, but the Eye he used to see things far away:

And suddenly he felt the Eye. There was an eye in the Dark Tower that did not sleep. He knew that it had become aware of his gaze. A fierce eager will was there. It leaped towards him; almost like a finger he felt it, searching for him. Very soon it would nail him down, know just exactly where he was. Amon Lhaw it touched. It glanced upon Tol Brandir he threw himself from the seat, crouching, covering his head with his grey hood.

and

... and then he saw, rising black, blacker and darker than the vast shades amid which it stood, the cruel pinnacles and iron crown of the topmost tower of Barad-dûr. One moment only it stared out, but as from some great window immeasurably high there stabbed northward a flame of red, the flicker of a piercing Eye; and then the shadows were furled again and the terrible vision was removed. The Eye was not turned to them: it was gazing north to where the Captains of the West stood at bay...

Could the Eye be the Palantir of Minas Ithil used by Sauron? Or was the Eye a special device?