decorative beach pebbles...just rocks covered in tar?

i'm setting up a new tank, and wanted to go with larger black stones as a substrate, so i decided to buy a bag of these at home depot. as i opened the bag i noticed that they felt kind of sticky and oily. i tried rinsing some pretty thoroughly, but it made no difference. now i'm told that my hand smell like road tar (i have no sense of smell, but willing to take someone's word for it).
so anyway, my questions are as follows: has anyone used these? did i just get a bad batch, and maybe should exchange them? if not, anybody have any recommendations for a sizable aquarium-safe black stone? lastly, anybody familiar with home depot's return policy?

I don't know about finding black rocks, but I can tell you to get the car off use baby oil. It'll melt it right off, your hands that is.

Walmart sells cheap 50lb bags of mexican river rock. You can toss out the lighter ones and end up with mostly dark gray to black small stones. Never had a problem w tar.


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Home depot will let you return anything

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