Osmium is both the densest and the rarest element that you can dig out of the Earth. It's so hard that it's used in places with constant pressure and wear, like the tips of fountain pens. One single cubic inch of this stuff weighs nearly a pound, and were you to somehow get a cubic foot of it, it would weigh over 1,400 pounds. Good luck with that, though: last year, the entire U.S. osmium production was only 165 pounds.
This is an image of the fractured, rocky surface of Mars. The Curiosity rover took this picture of "Marias Pass" which shows how two different type of rock units come together. Mudstone in the center of the image comes in contact with sandstone on top.
Assess what your students know about rocks with this simple Rocks Sort! Students cut out the facts and pictures and place in the correct spot for a great notes sheet! Check out these other rocks products: Types of Rock Book: Notes, Rock Cycle, Stations, Centers, Sort, Cut & PasteRock Observations Book- length & weight in metrics & english describe propertiesEarth Layers-What is Inside the Earth Book