Abstract: A safely encapsulated hazardous waste product free of unwanted leaching of contaminated metal constitutents and process therefor wherein a quantity of hazardous waste and a quantity of shale material characterized by having an aluminosilicate content containing at least 9.35% by weight of Fe.sub.2 O.sub.3, wherein the shale is reduced to a fine mesh before mixing, and defines a brick-like form as fired at about 1,150.degree. C. for a period of time to change the shale material into a semi-molten state and thereafter cooled to safely encapsulate the waste within the shale as a unit-handled product. The product of the invention satisfies and exceeds RCRA and LDR (EPA) requirements as shown by Toxicity Characteristic Leaching Procedure (TCLP) results.

Abstract: A leach-resistant vitrified composition, particularly suitable for long term encapsulation and disposal of nuclear wastes, comprises a high iron, high potassium aluminosilicate, fired at a temperature of at least 1850.degree. F. for at least 12 h.