Gemstones And Their Origins

By Peter C Keller
Van Nostrand Reinhold
1990 ISBN 0-442-31945-2

Van Nostrand Reinhold writes:

The closest most people ever come to experiencing gemstones at their source is at the jeweler’s case. This book takes you to many of their classic sources: the rich alluvial deposits of Sri Lanka, where precious stones lie exposed on gravel riverbeds; to Chantaburi-Trat, Thailand, where rubies are brought to the earth’s surface embedded in volcanic magma; to the black emerald-bearing veins of Muzo, Colombia; to the source of Australia’s Argyle diamond deposit—the most productive in the world, yet undiscovered until 1980.

Gemstones and Their Origins is the first major work devoted to the origins of precious stones: how they form, where they are found, and how they are recovered. Rigorous in scientific detail and lavish in illustrations, it explores the major geological processes responsible for the formation of gem deposits and then examines, on location, nine classic gem deposits from around the globe.

Peter C Keller takes you on a geologist’s tour of the world’s most famous and geologically significant gem deposits. Keller traces the origin of gems at each of four principle gem forming sources. First, we view the development of gemstones deposited by water on the earth’s surface. Here we encounter the gem gravels of Sri Lanka, opal deposits of Australia, and ruby and zircon from Indochina.

Next, we explore gemstones formed by molten rock—the hydrothermal emerald deposits of Colombia, the pegmatites of Minas Gerais, Brazil, and the rubies of Chantaburi-Trat in Thailand, brought to the earth’s surface in volcanic flows. As we go deeper into the earth’s crust, we encounter the world famous ruby deposits of Mogok, Burma, and jade deposits of northern Burma, one of few known examples of high pressure regional metamorphism.

Our descent into the earth’s crust ends some 100 miles below the earth’s surface. Here, in conditions of super high pressure and temperature, peridot and diamond form. Examples from the classic peridot of Zabargad and the recently discovered diamonds at Argyle in Western Australia are examined.

Along the way, Peter Keller documents this geological field trip with the outstanding photographs of Harold and Erica Van Pelt, renowned as the leading photographers of gems and mineral specimens in the world today. More than 100 stunning color photographs depict rough and cut stones and the often primitive places where they are mined. Useful maps, some in color, and an exhaustive bibliography make this the definitive reference work on the subject for gemologists and geologists, collectors and dealers, students and gem lovers.