Geology: Rock Lab

Rocks for Geology Lab. I've looked on the internet and the best and easiest way to find the properties of rocks is on www.wikipedia.org. Just type in the name of the rock in the search box of Wikipedia. You will not find a couple of the specific rocks, like different types of sandstone and limestone, but if you read the main article you will get some idea.

Can anyone guess what rock is this one on the left side?