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| proprietors of the Mar chienne-au-Pont, near Charleroi, Belgium, to construct there an experimental station for...made on the explosives used in the fiery pits of Belgium, thanks to which investigations one is able to...diameter, some black twill, the ordinary camera and lens, and a carrier to take lantern plates 3ïżœ X 3ïżœ inches...which slips over the lens. The length of the bamboos depends upon the focus of the lens and the amount of...tained to completely cover over the space between lens and negative, and hang down on each side. Of course |
 | | Journal (article/letter/editorial) |
| proprietors of the Mar chienne-au-Pont, near Charleroi, Belgium, to construct there an experimental station for...made on the explosives used in the fiery pits of Belgium, thanks to which investigations one is able to...diameter, some black twill, the ordinary camera and lens, and a carrier to take lantern plates 3ïżœ X 3ïżœ inches...which slips over the lens. The length of the bamboos depends upon the focus of the lens and the amount of...tained to completely cover over the space between lens and negative, and hang down on each side. Of course |
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| of gem transparency on the mirror F, through the lens L2 in the adjustable tube E. Covering the screen...the phosphorescence can be observed through the lens L,. In both tubes, E and D, the screw threads K...can be seen quite clearly, and even more so when a lens is used. In one such section a sequence of narrow...which is pink, are a pale straw yellow. But with a lens further variations are to be seen where each dark...mentioned, these products have to be designated as opal imitations, rather than synthetic opals. In two |
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| h e basic equipment required is :â (1) A single lens reflex camera (S.L.R.) with U . V . filter and cable...practically indestructible. If money were no object, a few lens manufacturers have produced special " macro " lenses...figure (the S.L.R. will have to be secondhand) a lens at that price is not being considered. (U.K. prices...purchased, there is no need to buy one with the standard lens having an aperture larger than f 2-8, as all photomacrographic...L D IN INCHES Image Scale of Reproduction 11 Lens Aperture in f 16 22 1:10 1:8 1:6 1:4 1:2 1:1 |
 | Murray, Richard W, Buchholtz Ten Brink, Marilyn R, Gerlach, David C, Price Russ, G, Jones, David L (1992) Rare earth, major, and trace element composition of Monterey and DSDP chert and associated host sediment: Assessing the influence of chemical fractionation during diagenesis. Geochimica et Cosmochimica Acta, 56 (7) 2657-2671 doi:10.1016/0016-7037(92)90351-i | Journal (article/letter/editorial) |
| quartz chert nodules investigated, in contrast to the opal-CT and quartz chert lenses, formed primarily by...as well. During formation of one Monterey opal-CT chert lens, REE/Al ratios show subtle distribution changes...itation recrystallizations. The opal-A * opal-CT and subsequent opal-CT * quartz transformations are...LARSON, 1975) , although intermediate phases such as opal-A â may also exist (e.g., HEINet al., 1978; WILLIAMSand...precursor sediment in which a given chert nodule or lens formed. Accompanying the Si02 phase transformations |
 | Snellings, Ruben, van Haren, Tom, Machiels, Lieven, Mertens, Gilles, Vandenberghe, Noël, Elsen, Jan (2008) Mineralogy, geochemistry, and diagenesis of clinoptilolite tuffs (Miocene) in the central Simav graben, western Turkey. Clays and Clay Minerals, 56 (6) 622-632 doi:10.1346/ccmn.2008.0560603 | Journal (article/letter/editorial) |
| Catholic University of Leuven, B-3001 Leuven, Belgium AbstractâMiocene rifting and associated rhyolitic...mainly of the diagenetic products clinoptilolite, opal CT, smectite, and celadonite. Electron microprobe...zones, clinoptilolite was replaced by authigenic opal CT and alkali feldspar, and the remaining clinoptilolite...heulandite, analcime, mordenite, erionite, phillipsite, opal CT, K-feldspar, quartz, and smectite. In general...The investigated zeolite deposit occurs as a tuff lens in the lacustrine KizilbuÌk formation and will be |
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| here described. An other is to illuminate the opal glass by means of a ern California are known to...about four times the effective diameter of the opal glass. 'J'he glass should be provided with a black...coast to the fresh-water Summer home on the of the opal glass. cone glass are readily calculated from...mould which curls them at one operation. Following opal glass and the area of the very approximately...between photometer reading and lumens incident on the opal glass is obtained. It should large, be noted |
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| Stratigraphy and Paleontology of the Carboniferous of Belgium.......... 19 () fc | Sr 22 Collecting at a Missouri...Splashes on White or Cream background (Cinnabar in Opal or in Chert); best green or green with hard (not...radiolaria, however, have shells of silica in the form of opal. When the shells sink to the bottom of the ocean...HARRELL 19 Paleontology Belgium L. STRIMPLE While stationed in Brussels, Belgium, with the Armed Services...observations on the stratigraphy and paleontology of Belgium. Extensive studies were not undertaken but it is |
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| working for you. LIGHT, to illuminate your SUBJECT, a LENS to collect ~he image and to project it on to the...illuminates the SUBJECT, in this case your negative; a LENS to project the image of the negative on to the LIGHT·SENSITIVE...and only allowed to pass through the negative and lens. It must not leak out at odd cracks and joints to...changed. Some method must be found for moving the lens towards and away from the negative for focusing...for good enlarging is to use a piece of flashed opal glass (NOT ground glass}. This is fitted at the |
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| c h , 1966. 69 I strongly maintain that in a "lens only' 5 identification-test a on mixed series of...the jeweller has only one "instrument"âa pocket lens, and proceed to consider what he can learn about...about gems with this as his only aid. A good lens is so vitally important that I do insistâmake it a good...hand. T h e n may follow close examination with a lens. T h e back facet edges may appear doubled, there...which you believe you can confidently identify by lens inspection onlyâprovided the specimens are clean |
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| submitted by the collectors P. Entremont of Antwerp, Belgium, K. Fischer of Starnberg, Germany, H.-J. MĂŒllenmeister...the source passes through a slit and achromatic lens combination called a collimator, which gives a light...finds that a pinhole can act as a simple lens. A 15 mm pinhole lens can form a good image of the sun, but...source, and not as an optical pinhole or simple lens. Problem 2 - "any light source will do" In his construction...centimetre scale, la shows a diamond pattern from a small lens-in-bulb torch held at 300 mm from the gem. lb shows |
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| stone by such a simple piece of apparatus as a hand lens, or a colour filterâ-which can be carried in...crystalline in structure; while others, such as opal (a hardened gel) and the natural glasses, do not...for instance) they would soon lose their lustre. Opal, and still more, pearl, coral and amber, are also...rubbed with the moistened finger and examined with a lens to ensure that it is a true scratch and not powder...careful scrutiny of the girdle of a diamond under a lens or microscope will often reveal small chips of which |
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| imperfections (Figure 16) can be observed with a lOx lens. Another form of silver concentration was encountered...described and compared to natural blue chalcedony, blue opal and stained chalcedony. The gemmological characteristics...dyed blue chalcedony, dyed blue quartzite and blue opal. In 1998 we found another material resembling blue...(Taiwan), natural blue chalcedony (Taiwan), blue opal (Peru). Photo by H.A. Hiinni, SSEF. imitations of...dyed blue chalcedony, dyed blue quartzite and blue opal, but the new product described in this paper may |
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| mixed in certain propor other is to illuminate the opal glass by means of a ern California are known to...about four times the effective diameter of the opal glass. 'J'he glass should be provided with a black...to be made, and blown upon with a copper of the opal glass. of the coast to the fresh-water Summer home...about called. From its An the filament to the opal glass and the area of the the air and fur are drawn...between photometer reading and lumens incident on the opal glass is obtained. It should be noted that large |
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| (an intricate piece of equipment) aided by a 10 x lens. The first impact of a gemstone upon the eye is...gemstone is afforded by that primary weapon, the 10 x lens. This to a gemmologist is as a rifle was said to...technical skills in the use of equipment, the 10 x lens must surely keep its place in the gemmologists'...the retention of (for right handed people)â 10 x lens in bottom right pocket, Chelsea filter in bottom...synthesis, that of opal, is in itself fairly characteristic in structure. The effect seen by lens is variously |
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| be blurred but still recognisable. (Example: fire opal and moonstone). Translucent. The stone will transmit... Resinous. As in amber. Waxy. As in turquoise, opal and jadeite. Creasy. As in nephrite and grossular...the silvery or pearly reflection shown by common opal, and is caused by the effect of light reflecting...surface layer of a stone, and, in the case of precious opal, is the result of the 3 'interference' of light...viewed through the table facet with a 6X or 10X hand lens. Anisotropic (birefringent) stones possess either |
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| and gem materials such as moonstones, horn, ivory, opal, turquoise, and tourmalines into a host of fanciful...Germany, Secessionstil in Austria, Palingstil in Belgium, and Modernism0 in Spain. Although nearly every...jewelr y while incorporating two gemstones, black opal and demantoid, that characterize the period. Courtesy...with a matte sheen set with turquoise and matrix, opal, amethysts, or baroque pearls. The lines often used...designer Archibald Knox created this 18K gold and opal necklace for Liberty and Company (c. 1900). Courtesy |
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| briefly stated: (a) A gel of low viscosity in which opal (2.00) will sink below the surface in about 10 seconds...various plastics (around 1.3). 2 (b) In this, opal will float, while quartz (2.65), diamond (3.52)...glance under the microscope or even with a pocket lens as to render a delicate density test an entire waste...FIELD ON THE Crystalling ~rystallinity of of ~~~~OPAL~ OPAL A A LTHOUGH LTHOUGH opals are widely believed...towards a regular arrangement of the atoms of the opal takes place during the formation of the gel. 10 |
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| topaz, peridot, jade, diamond, amethyst, citrine, opal. All of these latter have been used to a very large...of a lens only and have harped (monotonously) on double refraction of back facets and lOx lens to such...Vibration Directions at right-angles I I DIAGRAM 3 Lens metal discs nIAGRAM2 Semi-circles of polaroid forming...rightangles). circle of polaroid microscope tube Lens 288 ---1F~~~~~ directions of polarization were...construction are given. R.W. 294 STEVENS (D.). The OpalâQueen of Gems. P. & O . Lines quarterly "Posh". |
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| Crystals How Light Behaves in Gemstones The Pocket Lens and Other Accessories Hardness, Cleavage and Density...Tourmaline and Zircon Quartz, Agate and Chalcedony Opal Peridot, Sinhalite, Zoisite and Spodumene 9 page...and tourmaline H. Zircon I. Quartz group J. Opal K. Chalcedony group L. Jade minerals M. Lapis...refraction loa. Author examining a gemstone with a lox lens lob. Diamond balance arranged for hydrostatic weighing...may form later in crevices of sedimentary rocksâopal and turquoise being good examples. 28 OCCURRENCE |
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| synthetic rubyâbut it was! First examination with a lens and bench lamp over white mat paper showed distinct...amethyst colour in quartz. However, when one thinks of opal, it is usually a 'play of colour' which springs...basically white or black background or even Gidgee Opal (what an attractive stone!). In this case it is...recently we were shewn some specimens of colourless opal we were intrigued. These stones (we were shown four...hydrostatic weighings, but since we were dealing with opal they would have floated in that liquid, which has |
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| angular zoning could be seen with the aid of the 10 X lens or microscope (Figs 2 and 8). T h e absorption spectrum...seen on pink (conch) pearls (Fig. 3). With a 10 x lens this structure is easily seenâit might be lost under... whereas coral is about 2-70. * * * The 10 x lens in the hands of an experienced gemmologist is a...drill-holesâall can be exposed with judicious use of a lens. Its constant use makes one a better practical gemmologist...refraction can be very useful guides when using a lens only. We had in recently a half-hoop ring, set with |
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| courseof strippingoperationsin the Paguate mine a small lens of high grade uranium ore was encounteredimmediatelybelow...thatappears tobealtered frommontmorillonite; (3) Opal andchalcedony areabundant, andtheoreis unusually...highgrade. Blackore is dispersed throughout the lens. unaltered, occurin thesamples.An interpretation...Sucha mechanism presumably providedthe silicato form opal and chalcedony, whichwereimportantas cementsfor...15.6 8.2 0.8 2.5 sandstone 45.4 10.8 1.6 19.2 Opal and chalcedony 7.5 1.8 Calcite 0.0 0.0 65 |
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| natural gemstones Diamond Corundum Spinel Beryl Quartz Opal Alexandrite Topaz 7 Diamond Non-crystalline materials...interesting and unusual examples from the literature 11 Opal Summary Reports of interesting and unusual examples...diamond and passing from ruby, sapphire, emerald and opal to less well-known but equally beautiful species...allow the jeweller or the gemmologist with a 10X lens or simple instruments which can be used with little...testing to appreciate the phenomena observed. The 10 X lens has its limitations, however and the second part |
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| on the uppermost sheet of glass, with a sheet of opal glass covered by the 272 ROCKS AND MINERALS background...body can be avoided by fabricating an oversized lens hood made of black cardboard. A hole is cut in the...card board so it fits snugly around the end of the lens. A small wall made of black paper about one-half...eliminates reflections off the por tion of the lens that projects through the cardboard. This hood should...sheets of paper, cloth, or translucent plastic on the opal glass. The plastic permits the intensity of the |
