Weathering

Ah, the weather.  Rain, wind, snow, ice, heat and cold all affect the nature and appearance of the Earth's exposed rocks.  Rocks and minerals that are out in the open over time will change the way they look due to the weather.  The heat and cold will make the rocks expand and contract which can cause cracking and flaking.  The rain, wind, snow and ice will cause sharp points to wear away and the surface of the rock to appear dull.  When you come upon a rock and want to get a good look at it, you will need to use a rock hammer (or similar item) to break the rock and collect a small piece.  Look at the surface that was not exposed to the weather to see the true characteristics of the rock.