The Vedic equivalent to Mithra--Mitra--was born from the goddess Aditi. He actually emerged from a celestial egg, along with eleven other gods, making twelve total, not unlike how Mithras emerges from the rock--trees and pine cones as well--with the twelve signs of the zodiac in tow.
What's more, the goddess Cybele was also believed to be the mother of Attis, and who's name means Mountainous Mother, related to the Semitic gabal, mountain. So even in the Attis cult there seems to be some variation and association of the mother and the mountain/rock motif. There's even one depiction that I'm aware of Attis emerging from a rock alter
There also maybe some correlation between this and Adam, as Adam is made from the dust of the earth, and Christ is repeatedly compared to Adam. Indeed, the writer of the Gospel of Philip goes so far as to say this:
Adam came into being from two virgins, from the Spirit and from the virgin earth. Christ therefore, was born from a virgin to rectify the Fall which occurred in the beginning.
So is it too much of a stretch to call the rock that "begat"--(Justin Martyr)--Mithras both his mother and a virgin?
