Nothing stands out about the letter itself. The address symbol remains mysterious, but there aren't any hidden codes or anything in the words themselves.
As for the rock, it's difficult to identify without a strong background in geology and a way to test for radioactivity, but it's definitely a metallic element, about as hard as iron. It's got some weight to it for how small it is, meaning it's probably pretty dense. Other than the fact that it's, you know, glowing, that's about all that's readily apparent.
If the characters investigating the stone do have a background in geology and/or a way to test for or sense radioactivity, let us know! Also let us know if they choose to try to do anything with it, or experiment on it.
no subject
As for the rock, it's difficult to identify without a strong background in geology and a way to test for radioactivity, but it's definitely a metallic element, about as hard as iron. It's got some weight to it for how small it is, meaning it's probably pretty dense. Other than the fact that it's, you know, glowing, that's about all that's readily apparent.
If the characters investigating the stone do have a background in geology and/or a way to test for or sense radioactivity, let us know! Also let us know if they choose to try to do anything with it, or experiment on it.