Pyrite 
 
The ancient Incas used Pyrite for meditation and divination. Pyrite inspires the universal energies to activate the nourishing energies of the body. It encourages the ideal of health, intellect, and emotional well-being. It allows one to recognise the purity of the universe.
 
Do to the nature of rough stones, each is unique so may vary slightly from the picture. 
Our keyring stones vary from 2.5 -3 at their longest point.