Raw Black Tourmaline or Schorl
The Shielding stone
Properties: 
Tourmaline forms a protective shield around you. It is good for those with weak immune systems. It absorbs negative energy & turns it into positive – even our own destructive thoughts. Great in a stressful home or office. It also protects against cell phones, towers, electromagnetic smog, radiation, & psychic attack. Alleviates stress & grief. Promotes a calm attitude in the middle of complete chaos. When this stone is charged, by rubbing or heating, it becomes charged with one end positive and the other end negative. This stone is amazing when you feel overwhelmed-like you can’t deal with everything around you. It completely shields and balances you.

This stone helps with:
Lung issues such as bronchitis, pneumonia, asthma, etc.  It strengthens the immune system by helping to detoxify the body. Can help balance the emotions.
Chakra:
Root