Ok I need some help peoples. I'm working on putting together an african cichlid tank and I picked up a bunch of broken tiles (for free) from a local factory. They should be all natural stone tiles (I can see layers). The guy didn't really know what all of them were. I've given them all a once over with a tooth brush. I'm going to boil and then soak them overnight in different buckets (for water testing purposes). I know the light green chunks in the bottom of 1 are quartzite and the light brown ones are supposed to be slate. The blacker ones are where I'm at a loss of what they are (black slate maybe?). You can see the chunks of marble in there too, these are counter quality marble and not landscaping marble.
So I've marked which ones are supposed to be what and which ones I'm questioning. I have yet to do the boil or the over night soak so I might loose some in that process.
My question is what would the other ones be, and what would be the best way (outside of boiling) to clean them?