an abiotic complex organic solid that formed by chemistry from energy input into simple, cosmically relevant gases or solids. Shorter still, “abiotic complex organic gunk” works for me.
‘tholins’ (Gk ϴὸλος, muddy; but also ϴoλòς, vault or dome), although we were tempted by the phrase ‘star-tar’.
"Spectral analysis indicated water-ice highlands, coated with red tholins, organics formed by the solar irradiation of molecules such as methane or ethane."
- "Year One of our New View of Pluto", May-June 2016 The American Scientist (http://www.americanscientist.org/issues/pub/2016/3/year-one-of-our-new-view-of-pluto)