This is a magnetic developer purification structure that is used along with other stations positioned in the path of an electrostatic moving belt or drum in an electrostatic marking system. This purification structure may be a separate station or may be part of the development station provided it supplies purified developer to the development station prior to developer contacting the latent image on the drum or belt. The purification structure will agitate the developer mix to form a homogenous mixture of toner and carrier. This mixture is magnetically treated to separate less magnetically attracted contaminants from the remainder of the mixture. The contaminants are removed from the mix and substantially pure developer is then available for contact with the latent image.