I found a rock what is it?

This is a wood color rock that look Igneous on one side and is vary light. On the other side it has pronounced fibers visible and looks almost crystal but still the same color brown. The fibers are a lighter brown and here is the kicker it smells something of an organic vinegar. This rock was found on a city street with others having tiny labels and numbers like those in a museum so I have no info about where in the world it came from. What the heck is it?