This is an irregular Pyrite Cluster which displays a slight cubic formation. This piece has been fitted to be used as a keychain. Pieces may differ slightly from the examples provided.
Pyrite occurs in numerous shapes and habits. The smaller crystal may give off a beautiful glistening effect in light, and the larger crystals may be perfectly formed, including fascinating cubes, pyritohedrons and octahedrons. The perfect cubes of Pyrite embedded in a matrix from the famous Spanish mines are especially treasured among collectors.
This mineral's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold.
Dimensions below are averages for the crystal only, the chain length of the fitting is 6 cm.