r/Trinitite

When looking at Trinitite samples online, is it possible to judge very roughly how radioactive a piece might be by its appearance? Will having more glassy green areas exposed to the surface be an indication of a higher likelihood of more radioactivity than another sample of the same size with less green glassy area? Are there any other things to look for? Strictly speaking about how much radioactive activity is left, does the appearance even matter at all?