Geology Of World Gem Deposits

Each gem deposit-whether of primary origin in the parent rocks; or secondary as alluvial placers in valley floors, river gravels, or the sand of oceanic shelves presents an eloquent chronicle of the Earth's life story. It reveals to the expert the prodigious processes which formed the present crust of our planet, of which this volume discloses a small but exciting detail. The materials of the Earth's crust are the rocks. In this book, the author expounds on how they were formed, why they altered, why they became the cradles of precious gemstones, how they are categorized, and how they are now exploited by man. What initiates the growth of gemstones? How do they crystallize? Why do gemstones of the same species, originating from different sources, vary? What causes the occurrence of varieties? Why do diamonds, unlike other precious stones, occur not near the Earth's surface in its crust, but deep down beneath it in the upper mantle? These are only a few of the entrancing subjects discussed in this enlightening volume. The reader learns that the Earth is surprisingly alive and altering constantly-sometimes through slow and equable changes and at times by violent and tremendous cataclysms, events from which gemstones issue.

Understanding gemstones in a geological context Gemstones are colorful treasures of the Earth that have captivated humans for thousands of years. The physical and chemical characteristics of each type of gem provide insights into the geological processes that created them. Geology and Mineralogy of Gemstones is a textbook aimed at upper-level undergraduate and graduate students. It presents the basic mineralogical and geological knowledge needed to understand gemstones and examines the characteristics and geological origins of different types of gemstone. Volume highlights include: Concepts in mineralogy Structure and chemical composition of minerals Geological processes that lead to the formation and movement of gemstones Equipment and tools used to examine gemstones and their physical properties The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.

Gems have been used in the manufacture of jewellery and as ornaments since antiquity. Considering gems, recent statistics have shown that about 15 billion Euros are annually at stake. Nowadays, gemmology, i.e., the study of gem materials, is one of the most expanding fields in the earth sciences, positioned between academia and industry. As an applied science, in gemmology, the instruments used should be non- or microdestructive, and their cost should be reasonable both in terms of equipment and time consumption. Gemmology can also be used contribute to the development of pure science and in some cases, destructive techniques may have to be used. Taking into account the fact that gems are albeit rarely available for scientific research, this compilation of 20 articles by around 100 researchers from over 30 different institutions situated in 20 countries from around the globe, presented in the Special Issue entitled “Mineralogy and Geochemistry of Gems”, offers very good examples on the application of various methods for their study which will hopefully contribute to our better understanding of gem formation in general and will enhance scientific debates attracting more scientists from various disciplines to get involved in this field.

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