This stone is most known for healing, meditation and wisdom.   Used for expression of ideas and logic.  This stone works on the throat and brow chakras.  It can strongly affect changes in attitude about yourself.  Helps you be more objective and less critical about ways of dealing with existence.  It is a good stone for studying. The stone should be worn or carried around with you for a long period of time in order to reap the full benefits. 
Known for balancing body energy levels via thyroid, pituitary, lymph and other glands.  Helps with insomnia as well as neck, mouth, hearing and balancing blood sugar levels.
This is a cooling stone and is known to draw out infections, relieve sinus inflammation and high blood pressure.  Cools burns.
Highly suggested for balancing the metabolism.  Cleanses the organs and can boost the immune system.
Effective in combating the effects of natural and artificial radiation.  It is a good stone for those who work around x-ray equipment and radioactive material.
This stones Latin name is sodanum and is said to mean "a cure for headaches".
Too much of this stone can be exacerbating to anyone who is already in a long termed depressed state.
This stone should be cleansed once a week under warm water.