Book Reviews of Guide to Common Rocks & Their Minerals.

1. "An Illustrated Guide to Common Rocks and Their Minerals, by Vinson Brown and Dale Allan, weighs only two and a half ounces. That fact and its four by seven inch size make it easy to slip into a pocket. However, the 59 pages are packed with practical information. The book is divided into three sections that appear in logical order. The first explains how to identify the three main classifications of rocks: igneous, sedimentary and metamorphic. It tells how they were formed and how they appear to the eye. Line drawings are an aid. The second section concerns the minerals that are components of the rocks. The rock-forming minerals are listed in descending order of hardness from topaz to diatomite also known as diatomaceous earth. Pertinent information on identifying each is listed. This includes appropriate items such as specific gravity, color, fracture, cleavage, and habitat.

"Most terms are well-enough explained to be understood by the amateur. Others presuppose a certain knowledge of geology. It might be well to become familiar with all the vocabulary before taking the book into the field. An example of a cursorily defined geologic term is 'fracture, conchoidal.' Webster's Unabridged Dictionary says 'conchoidal--having elevations or depressions shaped somewhat like the inside surface of a bivalve shell.' "

"The value of Common Rocks is that it is more advanced, and therefore more useful, than many mineral handbooks. At the same time it is less detailed than a textbook. The third section is aptly called 'Naming Your Rocks.' The illustrations and descriptions are excellent and show the distinguishing characteristics of rocks with a similar casual appearance: 'Mica schist does not fizz, is not banded, and is thickly layered with numerous, shiny silvery flakes of mica.' Except for the back cover, the illustrations are not in color. This is deliberate. The authors say it is 'nonsense' to believe looking at a colored picture and then classifying specimens is all that is needed. They say that pictures can be misleading to the careless person and should be used only as secondary aids." (Betty Miller, Medford Mail Tribune, Dec. 16, 1976)

2. "The handbook is designed to give the new rock hound a basic groundwork for understanding and identifying common rocks. The reader will first study the general nature and the three main kinds of rocks, then learn about the minerals that make them. The last part of the handbook aids in the identification of rocks." (California Geology, July 1977, p. 166)