After reviewing the literature on the reaction of benzotriazole with copper surfaces and copper compounds as background for a study of the effect of benzotiazole on patina materials, the author reports on experiments he is conducting with cuprite, nantokite, paratacamite, malachite etc. He concludes that conversion of these materials to copper (I) or (II) benzotriazolate is usually incomplete and that in compacted minerals of natural patinas interaction will be restricted to accessible surfaces which would become coated with benzotriazole-containing products.