What Is Pyrite?
Pyrite is a metallic inclusion in the slate. Pyrites occur naturally in most natural slates.
The presence of pyrites is not necessarily an issue, but you should ensure your natural slates have been tested to BSEN 12326 and achieve the best classification “T1”.
All SIGA Natural Slates are T1 Certified.
Read more about markings on roofing slates.