Pure copyright freebase is a clear oil. However a slight impurity (one% or much less) can provide the yellow colour. If just one crystalizes several moments from hexane a pure products that if melted is clear could be received. Pure copyright leaves no residue when vaporized (adequately vaporized not burnt) https://edwinouwwx.madmouseblog.com/17141864/the-definitive-guide-to-chemical-structure-of-copyright