Iolite, "Vikings' Compass"

Like a crisp, dark winter sky, Iolite, in shifting shades of violet-blue carries the spirit of journey, of dreams and intuition, of exploration and illumination. Leif Eriksson and other Viking explorers who ventured far out into the Atlantic Ocean, away from any coastline that would help determine position, used thin pieces of Iolite as the world's first polarizing filter. Looking through an Iolite lens, they could determine the exact location of the sun and navigate safely to the New World and back. Iolite's name comes from the Greek ios, meaning violet, and is the gem version of the mineral Cordierite.

Iolite carries a violet-blue energy that activates and clears the Third Eye, opening communication and awareness from higher vibratory realms. Iolite may also link with, or stimulate, the Crown Chakra, located at the top of the head. 

Iolite honors Athena, the Greek Goddess of War and Wisdom. She is always depicted in armor and is known as a skilled fighter and strategist, and for her superb logic and intellect.

Violet and Indigo crystals also honor Sophia, Goddess of Wisdom and contradiction personified. She is the story of being lost then regained, the wisdom of understanding, doubting, and spiritual exploration without dogma.

References:-

[Ahsian, pp.] Robert Simmons & Naisha Ahsian, The Book of Stones (Berkley, CA: North Atlantic Books, 2007).
[Eason, pp. ]Cassandra Eason, The New Crystal Bible (London: Carlton Books Ltd., 2010).
[Fernie, pp.] William T. Fernie, The Occult and Curative Powers of Precious Stones (Blauvelt, NY: Rudolph Steiner Publications, 1973).
[Gienger, pp.] Michael Gienger, Healing Crystals (Scotland: Earthdancer Books, 2009).
[Hall, pp.] Judy Hall, The Crystal Bible (Cincinnati, OH: Walking Stick Press, 2003).
[Hall 2, pp.]Judy Hall, The Crystal Bible 2 (Cincinnati, OH: Walking Stick Press, 2009).
[Kunz, pp.] George Frederick Kunz, The Curious Lore of Precious Stones (New York: Dover Publications, 1971).
[Megemont, pp.] Florence Megemont, The Metaphysical Book of Gems and Crystals (Rochester, VT: Healing Arts Press, 2008).
[Melody, pp.] Melody, Love Is In The Earth (Wheat Ridge, CO: Earth-Love Publishing House, 1995).
[Raphaell, pp.] Katrina Raphaell, Crystal Enlightenment (Santa Fe, NM: Aurora Press, 1985)
[Simmons, pp.] Robert Simmons & Naisha Ahsian, The Book of Stones (Berkley, CA: North Atlantic Books, 2007).