Each stone varies. Phosphosiderite is a pretty rare stone that's really good for balancing the Third Eye (6th) Chakra and the Heart (4th) Chakra. People often use it to help connect to their Spirit Guides during meditation. Overall, this stone is a great healing tool and is particularly great to use for meditation because it calms one's energy field. 
Physically, phosphosiderite helps those with insomnia, heart ailments and the thyroid. It's also used to aid with colds/flus, lung/respiratory infections and abdominal tissues.