Page:Handbook of Precious Stones.djvu/11

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PREFACE.

Since 1882, when the "Handbook of Precious Stones" was published, the volume has been several times reprinted from stereotype plates. Occasionally a few alterations and corrections were made in the text, but no opportunity occurred to improve the arrangement of the work or to add fresh material. The present issue, however, represents a thoroughly revised edition. A large number of paragraphs have been wholly rewritten, while so many additions have been made to the accounts given of the different kinds of precious stones and other beautiful minerals that the 112 pages of the original handbook have been increased to 140. Among the minerals which have now received fuller treatment may be named diamond, sapphire and ruby, and the different varieties of garnet and of zircon. But readers who desire to make themselves more intimately acquainted with the optical properties, the crystal-forms and intimate structure, the modes of occurrence and formation and the chemical composition and constitution of precious stones, will find it necessary to turn to works in which full details of these subjects are given. In this connection may be named the treatises of Dana, of Professor Lewis of Cambridge, Professor Maskelyne and Professor Miers, for in the pages of the present handbook only such scientific considerations find place as can be easily grasped, and which, at the same time, help to explain the beauty of precious stones and afford methods of identifying the different kinds.

The chief localities where precious stones are found have been named in Chapter VII. under the headings of the several species and varieties. But this subject cannot be adequately discussed without having recourse