|MadSci Network: General Biology|
I have scoured the net to find an answer to your question, and I think I may have found it. I found several references to the presence of guano in mascara, or other cosmetics, but of course none were documented. I had my suspicions that guano itself was not being added (allergies, sanitation), but some component of guano may be added. Turns out, a compound prevalent in guano, guanine (a nitrogenous base) can provide an irridescent finish to paints and cosmetics. Here is an excerpt: Pearl is the original iridescent additive that customizes a finish. The base product comes from the interior lining of seashells (Mother of Pearl) or Guanine crystal, the derivative of sea bird and bat guano. When added to a translucent paint material, it alters the light ray within the film and bends or refracts the ray, giving off a secondary color. This action provides a completely new dimension of color--a refractive effect. Erin Cram, Admin MadSci Network
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