Field Book _of_ Common Rocks _and_ Minerals For identifying the Rocks and Minerals of the United States and interpreting their Origins and Meanings By Frederic Brewster Loomis Late Professor of Mineralogy and Geology in Amherst College With 47 Colored Specimens and over 100 other Illustrations from Photographs by W. E. Corbin and drawings by the Author G. P. Putnam’s Sons New York and London FIELD BOOK OF COMMON ROCKS AND MINERALS Copyright, 1923, 1948 by Frederick Brewster Loomis Twenty-sixth Impression Revised 1948 All rights reserved. This book, or parts thereof, must not be reproduced in any form without permission. Made in the United States of America Dedicated TO MY MOTHER WHO ENCOURAGED ME WHILE A BOY TO GATHER MINERALS, ROCKS AND FOSSILS. PREFACE Everyone, who is alert as he wanders about this world, wants to know what he is seeing and what it is all about. Here and there with the aid of capable guides a few have been introduced into the sphere of that wide and fascinating knowledge of Nature which has been so rapidly accumulated during this and the latter part of the last century. It is a full treasure house constantly being enriched, but unfortunately the few who have been initiated have soon acquired a technical language and habit, so that their knowledge and new acquisitions are communicated to but few. The public at large, not having the language nor an interpreter at hand, has come almost at once to a barrier which few have the time or patience to surmount.