Searching for a science fiction book about a young boy (preteen/teen) that travels to another world/planet (maybe multiple worlds). While he is on the planet(s) he collects a soil sample. Something about the soil was significant to the plot. Perhaps it allowed him to adapt to the environment of the new world, or maybe it transformed him physically to appear like the native species.
Unfortunately, I cannot remember any more detail. Every few years I decide I'm going to figure out what book this was, but after scouring lists of sci-fi book indexes, nothing jumps out at me. This is my first shot trying to use the public hive mind.
I would have read it some time between 1992-1996. I was in elementary school at the time and the book would have been age appropriate. I imagine it was a pretty short book, but I don't think it was considered a "short story." I think it stood on it's own, not as part of a collection. My dad checked it out from the library for me and it was one of my early exposures to science fiction.
If anyone has thoughts on this, I would be excited to hear them. Thanks!