Granite pegmatite crystals have long been admired by gem and mineral collectors as a source of fine specimens and gem materials. Pegmatites can host important deposits of ore minerals and industrial commodities, such as feldspar and mica. Their physical and chemical complexity presents daunting challenges to researchers who seek to better understand their nature and origins. With 209 stunning color photos and clear, authoritative text, this book provides a thorough discussion. Chapters cover pegmatite forms and distributions, interior structures, crystal, mineral, and gem pockets, and references for further study. Examples are from North America as well as worldwide.

Over 100 vivid color photographs of beautiful feldspar minerals show each species in its geological context. The feldspar minerals, as a group, make up nearly sixty percent of the earth's crust. Large crystals are found at many locales worldwide, in both igneous and metamorphic rocks. Often, feldspar forms the matrix for stunning gem crystals found in pegmatites. This book explains how feldspars are formed and the complicated structural features that create fine crystals, twins, and vivid colors. After a brief introduction, the general treatment begins with an explanation of the chemistry and taxonomy of the group. A section on their formation and geochemistry explains the kinds of environments where feldspars are formed. Detailed entries for each mineral provide locality information and full-color photos so that collectors can see what good specimens look like and which minerals one might expect to find in association with them. An extensive bibliography is provided for further study.

Quartz is prized by both mineral collectors and lapidary artists. Over 130 vivid photographs of these beautiful minerals are presented to show each mineral in its geological context. Superb examples are found in diverse geological settings from pegmatites to Alpine clefts and hydrothermal veins. The silica minerals are chemically simple, yet structurally complicated. Several high temperature and high pressure polymorphs are known. In addition to the polymorphs of silica, this book treats related minerals, including: lechatelierite, opal, and two natural clathrates, chibaite and melanophlogite. After a brief introduction, the general treatment explains the chemistry and taxonomy of the group. A section on their formation and geochemistry describes the kinds of environments where these minerals are formed. Then, entries for each mineral provide locality information and full-color photos so that collectors can see what good specimens look like and which minerals one might expect to find in association with them. An extensive bibliography is also provided.

Garnet, with its many color varieties, is a favorite of both mineral collectors and gemologists. Superb examples are found at many locales worldwide, in both igneous and metamorphic rocks. Other members of the group are prized by species collectors and micromount enthusiasts. Over 120 color photos of these beautiful minerals show each species in its geological context. This book also explains how garnets are formed and the unique conditions that create fine crystals and vivid colors. After a brief introduction, the general treatment begins with an explanation of the chemistry and taxonomy of the group. A section on their formation and geochemistry explains the kinds of environments where garnets are formed. Detailed entries for each mineral provide locality information and full-color photos so that collectors can see what good specimens look like and which minerals one might expect to find in association with them. An extensive bibliography is provided.

A comprehensive guide to the main varieties of birthstones, including their properties and structure. This volume features extracts from eight historical articles on the subjects of gemology and crystallography. This illustrative guide to birthstones is an ideal read for those who are interested in learning more about their spiritual connection to the natural world. Featured extracts taken from the following articles: - ‘Gems and Gem Materials’ Edward Henry Kraus - ‘The Natural History of Gems – Or, Decorative Stones’ C. W. King - ‘Diamonds and Precious Stones - Their History, Value and Distinguishing Characteristics’ Harry Emanuel - ‘A Manual of Precious Stones and Antique Gems’ Hodder M Westropp - ‘Precious Stones and Gems - Their History, Sources and Characteristics’ Edwin W. Streeter - ‘Gem Testing’ B W Anderso - ‘A Hand-Book of Precious Stones’ M. D. Rothschild - ‘Gem Stones and Their Distinctive Characters’ G. F. Herbert Smith