Depicted as a silver crescent within a white circle and with sixteen light blue petals, this is the Throat Chakra, or Vishuddha as it is also known. Panchavaktra Shiva is the deity of this chakra and in a certain kind of art which deals with lucid dreaming known as Dream Yoga it plays importance.
The Throat Chakra of course can be found in the throat as its name suggests and is the fifth chakra.
What is dealt with by this chakra is communication, independence, fluent thought and a sense of security. Expression shall be easy when the Throat Chakra is balanced. Clear expression and speech is also very much of this chakra.
When one has an imbalance of this chakra one will become uncommunicative, shy, and mousy. Suppression of what one really feels is also likely when there is an imbalance along with destructive and addictive behaviours.
Singing, chanting and humming happens to be great for balancing the Throat Chakra.