Floor panel and method of producing such a floor panel

A floor panel or wall panel, comprising a laminate of:

• a magnesium oxide based core layer comprising magnesium oxide and magnesium sulphate and/or magnesium chloride, wherein magnesium oxide and magnesium sulphate and/or magnesium chloride comprise 60-90% of the total mineral content of the core layer, wherein the core layer further comprises wood fibres;
• at least one magnesium oxide based upper crust layer positioned on top of said core layer, said upper crust layer comprising wood fibres;
• at least one magnesium oxide based lower crust layer positioned underneath the core layer;
• at least one upper reinforcing layer situated in between said core layer and said at least one upper crust layer;
• at least one backing layer situated on an underside of the lower crust layer;
• and
• at least one decorative layer and at least one wear layer attached to a top surface of the upper crust layer;
• wherein the density of said upper crust layer is at least 8% larger than the density of the core layer;
• and
• wherein the weight content of wood fibres in the core layer is larger than the weight content of wood fibres in the upper crust layer.