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  Kindle Edition:Studies on Agate

A Kindle edition of the book was created mid May 2012 and is available from you local Amazon website. The following links should take you directly to the appropriate website. Prices vary according to currency and any added VAT that is required for digital books. The UK price is 7-93 GBP.
Purchasers should note that the printed book is in colour but unless you have Kindle Fire, the download will be in b & w. However if a copy is purchased and you later buy Kindle Fire, then the colour version should be available for a free download.
In the meantime, the printed book has 47 coloured photographs and these have been saved and can be sent   as a complementary pdf (3Mb file size).  If you purchase the b & w Kindle version and would like the set of free coloured photographs, then please make contact via the link: Contact Me.







Book reviews received to date:

  1. “We also have an excellent chapter on agates from two contrasting places, Cumbria, England and Pilbara Craton, Australia; these two areas have had a remarkably similar history and therefore a similar story to tell."
    Down to Earth Issue 70, Feb 2010 (UK).
  2. "----------------- quality A4 print, offers very interesting work in nine major chapters of rich data and information about the current state of agate genesis research."
    Mineralien Welt  Issue 2 March 2010 (in German).
  3. “------- well produced book with masses of new information----. Investigative techniques are well covered. The section on agate genesis is particularly helpful."
    Rock n Gem (UK) Issue 47 Spring 2010.
  4. “----------a well written and illustrated scientific book on a fascinating bit of geology.”
    Deposits magazine Issue 23, Summer 2010 (UK).
  5. “The last chapter, “Agate Genesis”  is perhaps the most important --- it provides considerable information ----- in more detail than will probably  be found elsewhere."
    Rocks and Minerals September/ October 2010 (USA). The full review can be read on the Rocks and Minerals magazine web site.

Book Details:

The text introduces the reader to some of the scientific techniques that have been used to examine agate over the last 20 years; the basic scientific principles are explained in each chapter introduction. The book is intended for the lapidary worker and mineral collector as well as the more scientifically-interested members of the general public. The scientific methodology has been kept to a minimum and the text concentrates on the results. Over 140 references are given for those readers who wish to examine the cited sources.


Chapter 1        Agates from around the world
Around 30 regions world-wide are described. Agates from host rocks that are aged from 13 to 3500 million years have been used for scientific study.

Chapter 2        Petrological microscopes and photomicroscopy      
A full copy of Chapter 2 is included here as an Adobe PDF document and can be viewed by clicking on the following link: Sample Chapter.

Chapter 3        Electron microscopy
A number of interesting agate microstructures are revealed by the transmission and scanning electron microscopes.
Chapter 4        Powder X-ray diffraction
Basic descriptions of powder X-ray diffraction are given. This technique is particularly powerful in showing:   
1) Mineral phases in agate.
2) The age-related developing crystallinity of agate.
3) The changing moganite content. Most agate is a mixture of two forms of silica: moganite and quartz. The former decreases with age as it transforms into the latter.

Chapter 5        Visible, infrared and Raman spectroscopy
Results are shown from: 
1) Visible spectroscopy –identifying the effect of metal ions on silicic acid and colloidal silica. 
2) Infrared spectroscopy –identifying water and OH groups in agate.
3) Raman spectroscopy –identifying moganite in agate.

Chapter 6        Cathodoluminescence (CL)
Once again, the principles behind the technique are explained. CL can reveal hidden growth textures that are not visible in normal microscopy. The causes of CL are gradually being understood, and these have lead to a greater understanding of the microstructure of agate.

Chapter 7        High temperature and pressure studies
Immature agates show grain development when heated at high temperature and pressure. These studies have some application to what happens under normal earth-surface conditions.  A high temperature (~1200oC) allows the determination of the total water in agate showing an agate-age link.

Chapter 8        Agate from Cumbria, England and the Pilbara Craton, Australia
Agates found in these areas are very unusual: they are the only moganite-free agates that have yet been identified.  The agates from the 3500 million year old Pilbara Craton are the oldest reported agates described in the scientific literature. The Cumbrian agates are found near the Shap granite. Studies have demonstrated that the agates have an advanced grain growth caused by post-deposition heating. This natural heating has changed the appearance of the agates.
Chapter 9        Agate genesis
Discussion of agate genesis has been an on-going enigma since the beginning of the 18th century.  Over the last 15 years, more information about the microstructure has become available and slowly a greater insight into the origin of agate is being made. Nevertheless, questions on the nature and origin of the silica, method of silica transportation from source to gas cavity, the manner of crystallization are still mainly unsolved problems.

Index, References