Egg-shaped Boji Stone

An ovoid Boji stone from China. Spherical pyrite concretion with a metallic golden luster surface, a classic collector's format in the Boji stone category.

Boji stones are spherical pyrite concretions from sedimentary deposits. They crystallize as spherical aggregates of microcrystalline pyrite (FeS₂) in clay layers over long periods.

The Chinese deposits yield high-quality Boji stones in various shape variations. The typical metallic golden luster surface visually distinguishes Boji stones from other pyrite aggregates.

Pyrite is hard (Mohs 6.5) but can oxidize under unfavorable storage conditions. Dry storage is the professional preservation method.