Help me ID this rock

Kevin,

I would check it by dropping some vinigar on it to see if it fizzes. If it does, I wouldn't use it. I probably wouldn't use it all. I would also soak it in freshwater for a week or two.

Yes I have decided that I wont be using it. Its such a cool looking rock, but it scratches with my knife, and has some sort of metal ore in it I reckon. I will try the vinegar test when I get some vinegar just to see, but I bet it fizzes. Thanks!

I would not use it. It is definately a seemintary typ eof rock. The shiny thigs are mineral deposits, usually a metal. Sedemintary rock is generally soft, and is formed by deposits, generally from water movement. this would stand to reason seeing that you are from southern Texas. Generally, the rocks you want to use are those that were formed under pressure. Granite, quatrz, slate, and lava type fallout. All these are fairly inert and safe for the aquarium. Incidently, vinigar is not a very strong acid and it is better to test things with muratic. You can get it at most hardware stores..