Since you are at least a little in doubt about what it is you want to clean exactly and it is not obvious from the pictures exactly what the specimens are it is not going to be possible to tell you how best to clean them except in general terms. Assuming neither of the specimens is water soluble, start with soap and water and a toothbrush. It would be better to use one of the little fabric guns if you can afford one.(less than $100). It is not clear what it is you want to clean off of the "malachite" specimen. What is there about the malachite that you want to clean. It is not likely that you will enhance the value of the specimens very much since it is worth little or nothing to start with. Soap and water and the fabric gun may remove the white from the second specimen, is that is what you hope to achieve.