What Scales Look Like

Pure barium sulphate is hard dense white solid. Pure NORM scale can be like that (especially in tubulars).
More usually thin, eggshell-like, light or dark brown.
Can be stratified, like rings in a tree trunk.
Sometimes deep in the surface matrix, so not visible.
Separator sludges are granular suspensions.
Pig waxes are black tarry materials, often with chunks of rust and scale mixed in.