Are these rocks safe?

Steve is the one who is Correct on the sharp edges. These are round and tumbled. No edges to speak of. Thanks.

i researched this about a month ago before adding a rock that sported a lot of attached mica. Chemically the mica itself is  harmless, but Radek is correct re: the sharp edges.

Radek-
    As an aside, an additional concern that I have is if a rock/stone has anything that could damage eyes of some of the more clumsier fish like larger and fast-moving Tanganyikans.  These look smooth from afar, but I have pulled rougher stuff simply because of the potential damage to fish who dart around when startled.

    This may be a concern, albeit a mild one, for fronts (for example).

It has been just a bit more then 12 hours since I put the rocks in the tank. First of all, they look REAL nice. Fish look great, no heavy breathing or anything. Thanks everyone.

The vinager test is useful for finding out if there is any limestone in the rock.  As log as the limestone doesn't turn to mush it really isn't harmful in an East African cichlid tank since the cichlids like the hard water.

There was a test with Vinegar on the rock, if it sizzles then it will more then likely break down in the water and dissolve, raising and effecting water chemistry

Thanks everyone. Soaking and such, thats standard. Cobblestone works great too. I just want to know if there is anything in the composition of this rock that would be harmful.

Agree with them. I picked up 400lbs of Cobblestone from landscaping place, works beautifully

mica-schist i remember that from schoold thats the rock that you can peal the layers of it off i have a chunk of it around here from out west...........what aquaticclarity said sounds like a good plan

Rinse it off wel to get the dust and dirt removed and then soak a piece in water for a few days.  If the rock gets gritty or paste don't use it.  If it stays nice and clean it should be just fine.

Most quartz based rocks are just fine to use unless they have a high iron content rock mixed in with them.