u/probably-not-maeve

i found this plank washed up on the beach of lake michigan. i thought it was just stained this dark color but its even darker inside. no idea what it is

I’ve been doing some experiments without really looking anything up (i’m not working with anything dangerous, just messing around with some stuff)

I melted down some tin for a casting project i’ve been working on and got curious about the resulting slag. kind of on a whim, i freeze distilled some household vinegar (not sure on efficacy, so let’s call it marginally concentrated) and left the tin slag to sit in the acetic acid. it turned to sludge over the next few days while a stir bar agitated everything. i then turned off the stirring since it had gotten so viscous. the next time i looked several days later it had separated some. it was less sludgy and had developed little nodules. i added more acetic acid and more slag scrap and transferred it to a larger vessel to react and filtered it through coffee paper before returning it to the vessel.

the acetic acid evaporated at room temperature over the course of a few more days and the little nodules began to form crystals. long shoots with flat tops. they look a bit like fungal fruiting bodies. the material once fully dried is light, hard but very brittle.

my initial assumption was that it was crystallized tin oxide. i can’t find any existing results from doing something like this. my search results for similar things are only giving me info about precipitated tin oxide for use as a semi conductor.

after a second thought, it seems more likely that it’s tin acetate, right? although the preparation i’ve seen for that seems quite different from what i did

any thoughts/ideas about what happened here?