Agates: Treasures of the Earth

Book Review by Eric J. Hoffman


   Roger Pabian with Brian Jackson, Peter Tandy, and John Cromartie. Firefly Books, 2006. 184 pp, numerous color photographs, hardcover, 6 1/4 x 8 1/2 inches, $35


   Agates are the most common of gemstones, and yet they are infinitely varied and endlessly fascinating: no wonder that agates have been made into ornaments and adornments for over 7000 years. Finally, there is a book that gives agates the attention they deserve.

   Written by four highly respected mineralogists and filled with magnificent photographs, the book begins with a straightforward explanation of what an agate is. Exceptionally clear diagrams and text teach the reader how agates form, what causes the bands (which distinguish them from chalcedonies), and what causes the different colors. Special cases such as dendritic agate, tube agate, and the misnamed “agatized wood,” are discussed briefly but clearly, with first-rate photographs. A short (3-page) chapter briefly treats the physical properties of agates.

   The chapter “Sources of Agates” takes up the majority of the book (103 pp). It summarizes the geological environments in which agates form and describes the major occurrences. Since agates occur nearly everywhere, this description ends up being virtually a world tour, with typical examples of each agate type beautifully photographed.

   A chapter on lapidary techniques is well illustrated, showing every step involved in producing an agate cabochon and giving practical hints for the hobbyist. With agates so common one would not expect imitations and forgeries, but there is a section on these as well. Lesser agates are sometimes doctored to imitate rarer examples, and there is also a discussion of the gaudy dyed agates, mostly from Brazil.

   The chapter “Uses of Agate” is tantalizingly brief (12 pages). The discussion begins with 9000-year-old agate artifacts found in Mongolia and western Asia. Use of agate in jewelry probably began in Sumeria around 4500 years ago. The ancient Egyptians had their agate amulets, and the Persians their agate cylinder seals (a superb example is illustrated, along with its impression in clay). Unfortunately for those of us interested in ornaments, only eight items illustrate agate adornments over the millennia up to modern times. The chapter ends with a few pages on the uses of agate in science and technology, such as mortars and pestles, low-friction bearings, and so on. The book concludes with hints on collecting and contains a useful bibliography.

   This is a must-have book for the gemstone aficionado. The text is unusually clear and concise, and the photographs are done lovingly and with care. Clearly the emphasis is on the stone, with less to say about agate ornaments. But the agates themselves are so beautiful and endlessly varied that all those interested in gemstone materials will enjoy this book.


Copyright © 2006 by Eric J. Hoffman

Originally published in Adornment magazine, Vol. 6, No. 1, Winter 2007