On Sep 21, 2:02 pm, John DeBoo wrote:
Jeffrey St. Clair, Ph.D. wrote:

Are you sure it isn't slate? They look pretty similar as they're
geologically related. I do better with pictures so I thought I'd share one
that has a slate plate (lol) in the tank.

http://www.flickr.com/photos/ifnar/1...7601124618440/

Other than the color, it looks the same as in your pic. Mine is dark
gray and extremely dense. It looks more like solid rock as opposed to a
sandstone sort of look. It's rather heavy too. Time to hit the books
to better ID it.

Grandpa John

Sandstonme is a good stone to use as well. We do not have any stones
in this area, and all are imported from the north end of the state or
out of state. I never fail to stop and pick up a rock no matter where
its at if I see it laying there. Rocks area a premium so I sure do
not let them lay. I normally rtinse my rocks I find, and then treat em
with a dip of Potassium Permanganate or common househood bleach
(chlorox) rinse well and allow to air dry in the sun. Within 24 to 48
hours all traces of chlorox will have dissapated since air and sun
make it inert in short order, and they are good to go. I have slate,
shale and sandstone and in some tanks also use limestone. Limestone
will alter or can alter ph. Use white vinegar and drop some on rocks
your not sure of iand if it fizzies its linestone based. I know my
cichlids certainly would be disturbed if I took out my slate and shale
rock wall that literally covers the entire back of a 75 gal
tank.........never had any film come off any rock after I washed them
properly.....not saying it can't happen, but I have never seen it.