These are Pyrite / Fools Gold nuggets. They measure 45mm by 35mm approximately.
Photo is to show natural variation, and you get one of these fantastic pieces.
PyritePyrite is a stone of intellect and protection. It enhances intelligence, mental stability, logic, analysis, creativity, memory, and psychic development. It can help you tap your own latent mental talents and abilities. Pyrite is a powerful protection stone, and is very grounding. Pyrite is also known as Fool's Gold and Healer's Gold.