Quote Originally Posted by Shoden
but ive been thinking, does all materia have magical properties?
The indication given by the game is that they do. Even the White Materia, which Aerith thought useless, had a function.

Also, taking into account that all Materia is condensed, crystallized Spirit Energy, and that the knoweldge of those who have lived and died in the past (their memories, essentially) -- carried to the Lifestream when their Spirit Energy returned there -- is what interacts between the wielder of a Materia and Gaia, allowing the wielder to call forth Magicks, it's probably safe to assume that all Spirit Energy in the Lifestream has some memories attached.

Anyway, here was Sephiroth's explanation concerning the functioning of Materia:
"...the knowledge and wisdom of the Ancients is held in the
materia."
"Anyone with this knowledge can freely use the powers of the Land
and the Planet. That knowledge interacts between ourselves and the planet
calling up magic..... or so they say."