 | | Journal (issue) |
| pleochroism o > e. The absorption spectrum in the visible area consists of a broad absorption band at 15 800 cm...about 17 000 c m 1 to the blue end of the visible area, and a weak shoulder at about 24100 c m 1 . The...from 17 000 cm" * to the blue end of the visible area. The absorption at 24000 c m 1 is not responsible...useful gem material in the building industry is gypsum—the subtranslucent type is termed selenite, while...source in Montmartre (Paris) gypsum quarries. Slightly softer than gypsum is talc, being number 1 on Mohs's |
 | | Journal (issue) |
| Carlsbad, California Lucerne, Switzerland Bangkok, Thailand John L. Emmett Ren Lu Fanus Viljoen Brush...Richard W. Hughes Benjamin Rondeau Bangkok, Thailand Nantes, France Database Coverage Gems & Gemology’s...rocks of ruby from the John Saul mine in the Mangare area of Kenya (612 ± 6 Ma; Simonet, 2000), Longido in...from the placers of Bo Phloi and Kanchanaburi in Thailand, and Changle in China. The chemical field of the...magmatic and metamorphic origins. Within a single gem province in Australia, variations in color observed for |
 | | Book |
| the science of gem testing and have covered that area very well. Details of the geological occurrence...country rock is recrystallized over a much larger area the process is known as regional metamorphism. This...cavity the healing process operates over the whole area at once. Any liquid remaining which does not fit...Examples of twinning can be seen in rubies from Thailand and in the feldspar gemstones. Zones of growth...haloes. Siam rubies, as the stones from what is now Thailand are still known (the name is often given to any |
| | Book |
| the science of gem testing and have covered that area very well. Details of the geological occurrence...country rock is recrystallized over a much larger area the process is known as regional metamorphism. This...cavity the healing process operates over the whole area at once. Any liquid remaining which does not fit...Examples of twinning can be seen in rubies from Thailand and in the feldspar gemstones. Zones of growth...haloes. Siam rubies, as the stones from what is now Thailand are still known (the name is often given to any |
 | | Book |
| had prevented any real mining. Jake thought the area was worth a look. It was here, in the autumn of...April, enough snow had melted for a good look at the area. Hoover found the faint depression marked with the...Talc (1), the softest mineral, was followed by gypsum (2), calcite (3), fluorite (4), apatite (5), feldspar...locations as needed to spread the ore over a greater area for maximum exposure to the elements. equally desirable...Yogo Gulch and even into Kelly Coulee. Since this area was poorly suited for surface mining of the dike |
