A technique is described for the preparation of negative replicas for electron microscope study of carbonate rocks. Replicas are produced from carbonate rocks by chromium shadowing the replicating surface and then covering it with a carbon film which is scored into squares. The film is released by a versene (EDTA) solution which does not liberate CO 2 thus causing no damage to the replicas. The replicas preserve textural details and are simple and rapid to prepare. The method is applicable to limestones and dolomites of all types.