Welcome to Terry Moxon's Agate Web site.
Mineral genesis has never been an easy area for study. In many instances, rocks and minerals will have formed in a hostile environment over many centuries. It might be expected that the origins of agate, with an almost single mineral composition (> 98 % silica), would have been solved long ago. Unfortunately, simplicity in content has not allowed an easy insight into its genesis. After two hundred years, three key questions still remain in the realms of speculation. What is the silica source? How was it deposited? What crystallisation mechanism accounts for the banding?
I have been interested in the problems of agate genesis for over twenty years and this Web site discusses a possible mechanism for the banding in agate. Three agates have been chosen and a common line of investigation has been followed with all the specimens.
Fig.1. Shows a bulk section of agate prior to grinding down into a standard thin section: 0.03 mm thick.
Fig.2. At standard thickness, the agate becomes totally transparent and it is possible to examine the agate using the petrological microscope. A series of micrographs have been taken and used to build a collage for the thin section.
Fig.3. A second series of micrographs are produced by taking the images between crossed polaroids. These images show the internal structure and allow speculation about the growth of the agate.
Each agate is discussed on a single page.
Agate 1. Laguna agate (1), Mexico.
Agate 2. Burn Anne agate, Scotland.
Agate 3. Ethiebeaton Quarry, Scotland.
Agate 4. Laguna agate (2), Mexico.
The last additions to this site were on 1st January 2001.
In addition, you might be interested in my book on Agate Genesis. A sample chapter is included.
Terry Moxon can be contacted at tmoxon@auck.freeserve.co.uk.
Links to Other Silica Web Sites.
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