Colour of Precious Opal

  title={Colour of Precious Opal},
  author={John V. Sanders},
A Review of the Classification of Opal with Reference to Recent New Localities
Our examination of over 230 worldwide opal samples shows that X-ray diffraction (XRD) remains the best primary method for delineation and classification of opal-A, opal-CT and opal-C, though we foundExpand
Genèse de silice supergène sur Terre et implications sur Mars
La silice (SiO2), composant important des planetes telluriques, se trouve sous diverses formes. La genese de ses polymorphes amorphes et mal cristallises (opale-A, opale-CT, calcedoine) est encoreExpand
Paleomagnetic dating of ironstone nodules (‘nuts’) from the Yowah opal field, central southern Queensland
ABSTRACT To constrain the age of Australian opal formation, we have undertaken a paleomagnetic study of oxidised ironstone ‘nuts’ from Yowah, Queensland. Following standard methods, we haveExpand
Designable structural coloration by colloidal particle assembly: from nature to artificial manufacturing
This review focuses on the design of artificial structural colors based on colloidal particle assembly and summarizes the functional bioinspired structure colors and demonstrates the design principles of biomimetic structural colors via the precise structure engineering and typical bottom-up methods. Expand
Silicon-Oxygen Region Infrared and Raman Analysis of Opals: The Effect of Sample Preparation and Measurement Type
An extensive infrared (IR) spectroscopy study using transmission, specular and diffuse reflectance, and attenuated total reflection (ATR) was undertaken to characterise opal-AG, opal-AN (hyalite),Expand
The Era of Nanoparticles : Gravity Is Not Sufficient Anymore
The sedimentation of particles is a long-standing phenomenon in nature. One of the most impressive examples may be the formation of opals where the sedimentation of silica particles gradually formsExpand
Ultracentrifugation Techniques for the Ordering of Nanoparticles
This review summarizes the work back to the 1990s, where intuitive use of centrifugation was achieved for the fabrication of colloidal crystals to the very recent work where analytical (ultra)centrifugation is employed to tailor-make concentration gradients for advanced materials. Expand
Aberystwyth University Chromaticity of structural color in polymer thin film photonic crystals
A three-dimensional goniometric study of thin-film polymer photonic crystals investigates how the chromaticity of structural color is correlated to structural ordering. Characterization ofExpand
An expanded state diagram for the directed self-assembly of colloidal suspensions in toggled fields.
The suspension structure and assembly kinetics of micrometer-diameter paramagnetic spheres in toggled magnetic fields are investigated and the existence of fluid, columnar, percolated, and ellipsoidal-shaped microstructures agree well with those predicted by the theoretical and computational work of Sherman et al. Expand


Structure of Opal
SINCE the work of Flörke1 it has generally been accepted that natural opaline silicas fall into two broad categories: (1) specimens which give X-ray patterns indicative of an obviously, although inExpand
Über Bragg‐Reflexe mit sichtbarem Licht an monodispersen Kunststofflatices. I
Mit Hilfe von Durchsicht- und Reflexionsspektren werden die Farberscheinungen an monodispersen Latices als Bragg-Reflexe mit sichtbarem Licht identifiziert. Durch eine vollstandige StrukturanalyseExpand
The opal book
The crystal structure of Tipula iridescent virus as determined by Bragg reflection of visible light.
It is concluded that the (hydrated) virus particles in the crystal are not in contact but are separated by large distances of water, and the crystals are thus probably held together by long-range forces operating at a distance comparable with the size of the particles themselves. Expand
The structure of opal and the origin of its iridescence
SummaryA study of the optical behaviour of iridescent opal indicates very clearly that the silica present in the material has a regularly stratified structure in which the alternate layers differ inExpand
Die Optik der Edelopale
Inhalt . Einleitung 183 1. Die homogenen Louchtkömer 184 2. Methodisches 185 3. Beschreibung der Erscheinung 187 4. Die verschiedenen Reflektogrammtypen 189 ö. Großzwillinge 196 6. Allgemeines zurExpand