Geology Word of the Week: R is for Rock

"In spite of the difficulty in defining rocks, most rocks are easily recognized when you see them, and most are made of minerals or mineral-like substances. They are usually solid, hard, and heavy, compared to the other materials you see and use daily."
-From Rocks and How They Were Formed by, Herbert Zim, Golden Library of Science, 1961.

Carbonate rocks, peridotite rocks, mountains, and field vehicles, Oman, January 2010.

def. Rock:
1. A solid mass of matter-- usually composed of one or more minerals or mineraloids-- that occurs naturally on the Earth or another planet or extraterrestrial body.
2. What geologists study.