The white howlite stone is believed to help teach patience, and overcome self criticism. It is also a very calming stone used to relieve stress of all kinds. It makes an excellent antidote to insomnia due to an overactive mind.
Zodiac - Gemini 
Element - Air

Smokey Quartz is associated with the solar plexus chakra, and known as an excellent ground stone. Many believe it aids in relieving stress and anxiety, while calming a hyperactive mind. Smokey Quartz is also said to disperse fear and lift depression and negativity, while encouraging positive thought and action. Others associate the stone with detoxifying the digestive system, and protecting against radiation. Typical colours are Brown and Black.
Chakras - Base Chakra, Solar Plexus Chakra 
Zodiac - Scorpio, Capricorn 
Element - Earth/Air