In August I went to Big Bend National Park in western Texas.  It was full of too many amazing things for a four day visit.  Our first night there I noticed a curiosity embedded in the rocks near our campsite (see image below).  The little balls seem to contain iron (because of the coloring due to iron oxide).  While watching an update on the Mars Rover mission, I was reminded of the ‘blueberries’ first discovered in the crater that one of the rovers bounced, rolled, and jostled into.  These little rocks are now thought to be composed of hematite, a mineral (iron(III) oxide) that is found all over the Earth and is a major source of iron.  The Wikipedia article on hematite is pretty good.

If you haven’t already seen it, check out Google Mars. Also, see what’s involved in getting to mars.