These are colour additives which are insoluble in the medium to which they are added (do not dissolve in water or oil). They are generally very stable and do not bleed/migrate and are therefore very popular for soap making as they are also very cost effective. They do however have a tendency to “clump” so they need to be mixed very thoroughly in oil before adding them to your soap base. If you wish to use these colours in melt and pour soap base you will need to mix them with glycerin first otherwise they will cause "speckling".
Oxides and pigments are usually cosmetic grade and can therefore be used for mineral makeup and soap making as well as crafts, cement colouring etc. They are commonly used for creating matte eyeshadows, blush, lip stick and foundation.