Primitive grain clumps and organic compounds in carbonaceous chondrites

Refractory interstellar grains acquire tarry polymeric coatings in dense pr otostellar molecular clouds. Collisions between polymer-coated grains lead to the formation of micron sized grain clumps that are subsequently expelle d into the diffuse interstellar medium. Such grains could contain the build ing blocks of life such as amino acids in their interiors protected from di ssociative ultraviolet radiation.