Gems and Precious Stones; With Descriptions of Their Distinctive Properties, the Methods for Determining Them, &C

Gems and Precious Stones; With Descriptions of Their Distinctive Properties, the Methods for Determining Them, &C

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 edition. Excerpt: ...this stone, and it was largely used by them as engraved signet rings. Down to the last century the "jargoon" was much used in mourning ornaments, and was then considered to be an inferior diamond. Mr. Streeter says that he has in his collection a green zircon weighing carats, having the lustre of the diamond, and surpassing the emerald in colour. Zircons are cut for ornaments, by grinding on a leaden plate with emery powder, and polishing on a copper plate with powdered rotton-stone. The "jargoon" is commonly cut in the form of a rose-diamond or as a brilliant; the "hyacinth" is cut like a brilliant with a rounded table. The zircon occurs in granite and syenite, also in crystalline limestones, gneiss, chlorite schist, and other metamorphic rocks; it is sometimes found in volcanic rocks, and also in beds of iron-ore. It is also found in alluvial deposits with other gem-stones, and in auriferous sands in many parts. Its characteristic features are its crystalline form (the tetragonal prism often terminated at both ends by the tetragonal pyramid), its high specific gravity, and the property the coloured specimens have of becoming colourless or almost so when highly heated. In the Townshend collection at the South Kensington Museum are twentyfive cut specimens of the different varieties of the zircon, some of which are very fine stones. Several were obtained near Mudgee, in this Colony, one of which is classed as being a true " hyacinth." Among the collection are zircons of a variety of colours--green, brown, orange, lavender, &c. In New South Wales zircons are common in the auriferous river sands and drifts. They are, of course, when thus found, more or less rolled. They are found in granite on the Mitta...
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Product details

  • Paperback | 52 pages
  • 189 x 246 x 3mm | 109g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236618750
  • 9781236618757