Where to get slate or other flat type of rocks

ok...here's what i did:

I took a soft brass brush and brushed em over good under hot tap water. Then I boiled them (nice rolling boil) for over an hour, changed the water and then boiled them again for over an hour.

What I like was when I took the pot outside and drained it, the rocks almost dried instantly. I think it's safe to say that they were extrememly hot. ;o)

Should this be good or is there something else I need to do?
 
Do you have a rock quarry where you live? They sell different types of rocks, usually including slate. I used to visit the local quarry to buy stones when I was into sculpting. Look it up in your yellow pages or the internet.
 
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