Genesis and Classification of Agates and Jaspers: a New Theory


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  • Author: Marco Campos-Venuti
  • Language: english
  • A4 format
  • 620 grams
  • 160 pages, 437 figures and 22 diagrams
  • Shipping with DHL

This book shows a new geological model that explains the formation of most microcrystalline and amorphous varieties of silica. These stones are formed thanks to the precipitation of silica polymers according to wet-dry seasonal cycles.

Availability: 198 in stock

SiO2 accounts for 3/4 of the earth’s crust. Its crystalline forms are well known and their properties well studied. On the contrary, the microcrystalline forms of silica have given many problems to scholars. Agates, jaspers and flint are still considered materials of mysterious origins, despite being found in a number of distinct geological settings. At the basis of their difficult understanding lies the fact that they are not crystalline materials, but silica polymers. For this reason the classic rules of crystallography and mineralogy do not work here, following instead the physics of polymers and colloidal solutions.
This book shows a new geological model that explains the formation of most of the varieties of Jasper and Chalcedony, in term of two different silica polymers. They are formed as concretions in surface rocks. This leads that silica varieties take their origin in a meteoric environment with a strong influence due to the weather and the alternation of dry and wet seasons. Uncountable situations are possible due to the many parameters as the host rock, the pH of the water and the weather, that explain the numerous existing varieties of silica.
This book was written in simple words and aimed at a wide audience. It is targeted to collectors, geologists and the curious, analyzing many collectible varieties of jasper, agate and chalcedony. The use of an innovative geological and microstratigraphic approach to the topic leads to the consequence that most of the concepts are original. The explanation of genetic phenomena is developed with the help of a large number of pictures and diagrams that capture the reader’s attention.

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