Hawk's eye also known as Blue Tiger Eye or Falcon's Eye is a blue-gray to blue-green opaque gemstone variety of fibrous quartz.
Hawk's eye is famed for its chatoyancy, reminiscent of the 'eye of a hawk'. It is closely related to tiger's eye and pietersite, both of which exhibit similar chatoyancy. Tiger's eye is actually formed from hawk's eye. As blue crocidolite is dissolved by quartz, traces of iron oxide remain; less iron tends to result in the blue color of crocidolite and if more iron is present, color tends to result in the brownish golden color of tiger's eye.
Hawk's eye is believed to be a stone of protection, often used by travelers. It can also be used to help protect against the negative energy of others. It is associated with the planet Jupiter and the astrological sign of Sagittarius. Its energy is known to help balance the brow chakra.