Abstract: A method of detoxifying hazardous wastes containing mercury, zinc, selenium, arsenic, antimony, or thallium by mixing the waste with silicate and a setting agent which together form an alkaline silicate matrix. An additive other than the silicate and setting agent is mixed with the waste, prior to the matrix setting, to form a complex with the mercury, zinc, selenium, arsenate, antimony, thallium, or copper that is substantially insoluble in the environment of the alkaline silicate matrix. The alkaline silicate matrix thereby binds wastes which could otherwise leach out to contaminate the environment.