Iran is certainly heterogenous in its physical composition. Racially Iran is overwhelmingly Caucasian, only small minority groups differ. The main composition is the Mediterranean subrace. But the Mediterranean race is huge and sub-divided into multiple groups. The gracilized Mediterranean type, the most purest Mediterranean, is far more common in Arabia and more or less a small minority in Iran.
Along with other Mediterranean types such as the Atlanto-Mediterranid, Pontids, and an unusual coastal Mediterranid type, these Mediterranean subraces comprise a small portion of the population. Indeed these are found mostly in Southwestern Iran.
The Dinaric subrace, represented mostly by Armenoids. Although widespread throughout Northern, Western, and Central Iran, it increases in frequency towards the NorthWest of Iran, the closer one gets to the Caucasus mountains.
The main composition of Iran is in the Irano-Nordoid or Irano-Afghan subrace. This branch of the Mediterranids comprises the overwhelming majority in Iran. This long-faced type is the main element on the Plateau.
Alpinids are also found in to a small degree, especially in the Western mountains among Bakhtiari tribes. They are relatively insignificant and will not be discussed.
NOTE: Not all pictures are of Iranians, but all illustrate the basic physical types.