re: no drape, no forceful displacement
no coloring of surrounding matrix, perfectly spherical form with no gravity deformation -
tektites formed out of impact plumes, gradually condensing to larger spherule sizes than seen on Earth due to Mars' relative lack of atmosphere and low gravity
What is the platinum element group distribution in these things? Why hasn't anybody bothered to get them?
My guess: for the same reason they have not re-imaged the formation where you spotted out-gassing.
My bet: Some water, but damn little, with most it forming either sulfuric acid or brines.