AceShowbiz - Ahead of the release of "Avengers: Age of Ultron" Blu-Ray and DVD edition, a new featurette has surfaced online. The featurette entitled "Infinity Six" features the history of the Infinity Stones and shows how four of the six Infinity Stones have been introduced in previous Marvel movies.
The Infinity Stones are the most powerful objects in the universe and also Thanos' biggest obsession. Thanos is dying to have all of those stones because when those stones are combined and placed into the Infinity Gauntlet, they make whoever holds them become invincible.
The featurette provides detailed information about the stones which fans need to know before watching "Avengers: Infinity War Part I". The Space Stone is the Tesseract, previously seen in "Captain America: The First Avenger" and "The Avengers". The Reality Stone is the Aether, introduced in "Thor: The Dark World". The Power Stone is the purple gem housed by the Orb in "Guardians of the Galaxy". The Mind Stone was the one embedded in Loki's staff in "The Avengers", but now it resides in the Vision's forehead, as seen in "Avengers: Age of Ultron".
While the four stones have already appeared and played some parts in previous Marvel movies, there are two other stones have yet to be seen, the Time Stone and the Soul Stone. There are some speculations that the Time Stone will be featured in "Guardians of the Galaxy Vol. 2" and the Soul Stone will pop up in "Doctor Strange".