Has Marvel Studios just given away a small hint as to where the Soul Stone is?
As you will see from the image released by Marvel each stone is represented by an Avenger....

Space - Captain America
Power - Peter Quill (Guardians)
Reality - Thor
Soul - Iron Man
Time - Dr Strange
Mind - Vision
So why Stark? all the other stones have been found or discovered inside items....
Space - Tesseract
Power - Orb
Time - Eye of Agamotto
Reality - Aether lantern
Mind - Sceptre
Soul......??
This is a very interesting concept, and does this hold the key as to where to find the missing stone?