Smoking for decades, dr showed me photo of autopsy, is the black specks on lungs from excess iron or something?

Soot. That is how the entrapment of partially burned or charred tobacco soiling the lungs of a smoker looks. Look in an ashtray for a good visual analogy.
Anthracosis. Black specs are called anthracosis. They are particles of soot, tar, and other environmental pollutants that we breathe in and are filtered out of the air by our lungs. The body cannot dissolve or absorb them, so they deposit over time. Everyone has some, but usually it is much heavier and darker in smokers.