Midterms, help!

Just finished two, back to back, in geology lecture and lab. All about rocks, igneous, sedimentary and metamorphic. Some of them look an awful lot alike, like shale and slate, marble and crystalline limstone. And I know the teacher says she picks specimins that are comparable to what we have studied in our little buckets, but man, there were some surprises on the test in lab. We jumped up and down, pouring acid on those white ones to see if they fizz (calcite), or scratching away on the little glass thingy, or on our fingernails, or with our fingernails, and still scratching our heads. Considering there were about 45 of those suckers, I think Susie and I did pretty well. We studied and categorized bucket by bucket, then dumped them all out and did the whoe shebang, rock by rock. I decided that if I didn't know what it was, it must be wacke (pronounced wacky), because I could never remember that one. It looked like any hunk of stuff you might pick up by the side of the road, kind of gray and dull and not very interesting. Nature is infuriatingly diverse in the multitudes of stuff out there, and pieces of the same stuff can look might different, too. Whatever, we are moving on to reading topographical maps. Whoopee.