Apophyllite is a hydrated potassium calcium silicate crystal.  The clear or white crystals are the most common.  The green is rare.
Green Apophyllite is most known for helping to link man with nature.  For those of us who have become too caught up in a world of artificiality, a world of electronic gizmos and living in condos, being able to get back in touch with nature is an important step in becoming more spiritual.  It is particularly reputed to aid in opening the psychic channels that allow us to communicate with animals.  It helps you become more aware of nature and more environmentally friendly.  On the spiritual side, it helps you see the spiritual in all of creation.  It is also said to help in decision making, especially decisions of the heart, by helping us to see all sides clearly.  The associated elements are wind and earth and the energy centers, or chakras most energized by this stone are the heart, third eye (forehead) and crown (top of head) centers.  Physically, it aids in removing toxins from the body and recovery from illness and injury.