Contents

28 November 2014
Vol 346, Issue 6213

About The Cover

Cover image expansion

COVER A 239-gram piece of NWA 7034, or "Black Beauty," a 4.4-billion-year-old meteorite from Mars. The rock, valued at more than $10,000 per gram, is both the oldest martian meteorite and the first one made of pieces that were once eroded by wind or water. One of more than a dozen pieces that fell into the Sahara desert, this sample was the first to be recognized as martian. See page 1044
Photo: © Joe McNally