scholarly journals Characterization of Coloured Gemstones by X-ray Micro Computed Tomography

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 178
Author(s):  
René Heyn ◽  
Abraham Rozendaal ◽  
Anton Du Plessis ◽  
Carene Mouton
Keyword(s):  
Computed Tomography ◽  
Low Cost ◽  
Micro Ct ◽  
Fracture Detection ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Complementary Method ◽  
Color Changes ◽  
Non Destructive

The monetary value of gemstones is based on five variables: rarity, cut, weight, color and clarity. The latter refers to internal impurities and defects. Fashion may also dictate demand and price. To enhance some of these features and value, gemstones are treated. Disclosure or nondisclosure thereof has been controversial and affected consumer confidence. Most of these treatments are difficult to detect with the naked eye and accurately quantify with traditional optical and analytical methods. X-ray micro computed tomography (micro-CT or μCT) is proposed as a relatively low cost, physically non-destructive and complementary method to detect and quantify clarity enhancement and also to provide a unique 3D fingerprint of each gemstone. A collection of 14 cut colored gemstones was selected. Micro-CT scans allowed fracture detection, their distribution and calculation of filler volume as well as 3D mapping of inclusions, surface and internal imperfections and artificially induced modifications. As a result the method allows the construction of a digital twin. X-ray exposure could however induce unwanted color changes. This effect was minimized or eliminated by optimizing dosage and exposure time.

Spectral X-ray tomography for 3D mineral analysis

2020 ◽  
Author(s):  
Jonathan Sittner ◽  
Jose R. A. Godinho ◽  
Axel D. Renno ◽  
Veerle Cnudde ◽  
Marijn Boone ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Ore Deposits ◽  
Chemical Information ◽  
Micro Ct ◽  
The European Union ◽  
Mineral Analysis ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Analytical Technique

<p>Image based analytical tools in geoscience are indispensable for the characterization of minerals but most of them are 2D techniques, limited to the surface of a polished plane in a sample. X-ray micro computed tomography (micro-CT) is becoming a common analysis technique in geoscience and provides direct 3D information of the internal structure of a sample. A major drawback of micro-CT in the characterization of minerals, however, is the lack of chemical information. There have been different approaches to obtain chemical data using micro-CT but most of them are time consuming and difficult to adapt to regular use.</p><p>Therefore we introduce a potential new analytical tool: Laboratory-based Spectral X-ray Micro Computed Tomography (Sp-CT). Results from a spectral imaging detector prototype, installed inside a TESCAN CoreTOM micro-CT scanner, will be shown. This new analytical technique enables to obtain both high resolution structural and chemical information in 3D. With this information, the mineral distribution inside unbroken rocks and particles can be identified and quantified.</p><p>Based on the transmitted energy spectrum of a sample, main elements can be distinguished and minerals classified. It is also possible to quantify heavy elements within particles of complex composition and the measured sample volume is significantly larger compared to conventional analytical 2D techniques. Furthermore, Sp-CT is non-destructive and does not require sample preparation.</p><p>Sp-CT will open exciting new possibilities for mineral analysis. With this new technique, the 3D properties of the particles can now be measured and used for example in process mineralogy simulations. This is a major improvement to current simulations that predominantly use less representative 2D or bulk particle properties. Moreover, the Sp-CT could potentially be used as an alternative technique for regular characterization of ore deposits and processed ores since more representative volumes can be analyzed in a fast manner relative to existing techniques.</p><p>This research is part of the upscaling project “Resource Characterization: from 2D to 3D microscopy” and has received funding from European Institute of Innovation and Technology (EIT), a body of the European Union, under the Horizon 2020, the EU Framework Programme for Research and Innovation.</p>

scholarly journals Applying micro-computed tomography for porosity analysis of polypropylene modified with microspheres

2021 ◽  
Vol 332 ◽  
pp. 01017
Author(s):  
Piotr Szewczykowski
Keyword(s):  
Computed Tomography ◽  
Solid Material ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Material Density ◽  
X Ray ◽  
Blowing Agent ◽  
Central Measuring ◽  
Porosity Analysis ◽  
Non Destructive

Porosity of polypropylene samples was investigated by applying X-ray micro-computed tomography (micro-CT), which is getting more and more popular as a non-destructive method. Microspheres were applied as a blowing agent at three concentrations: 3%, 6% and 9% by weight. Tensile testing specimens were obtained by injection molding technology and its central, measuring part were examined by micro – CT. Results were compared to porosity calculated based on difference in porous and solid material density. Pore size distribution curves were discussed as well.

scholarly journals Radiological characterization of gilthead seabream (Sparus aurata) fat by X-ray micro-computed tomography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Diana Ceballos-Francisco ◽  
Nuria García-Carrillo ◽  
Alberto Cuesta ◽  
María Ángeles Esteban
Keyword(s):  
Computed Tomography ◽  
Sparus Aurata ◽  
Gilthead Seabream ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Radiological Characterization

Non-Destructive Assaying Gold Jewellery Using Dual-Energy Micro-Computed Tomography

2015 ◽  
Vol 73 (3) ◽  
Author(s):  
Jaafar Abdullah ◽  
Abibullah Samsudin ◽  
Nor Laili Omar ◽  
Hafizza Abdul Manan
Keyword(s):  
Computed Tomography ◽  
Matrix Effects ◽  
Visual Observation ◽  
Dual Energy ◽  
Micro Computed Tomography ◽  
Tomographic Images ◽  
X Ray ◽  
Challenging Tasks ◽  
Tomography Method ◽  
Non Destructive

Determining the fineness of gold jewelleries remains one of the most challenging tasks in gold trading. The existing technology of gold testing is inadequate, allowing gold counterfeiting worldwide. The most popular non-destructive method for analysis of gold jewelleries is X-ray fluorescence technique. However, the technique is limited to surface only and it is also greatly influenced by matrix effects. In this paper, dual-energy X-ray micro-computed tomography method was proposed to assay gold jewelleries. Experimental results demonstrated that grey values of reconstructed tomographic images in combination with advanced image analysis procedures could be used to detect fake jewelleries. Due to the uniqueness of X-ray absorption, the technique was also capable of identifying different materials in gold jewelleries. Further analysis on sectioned-earrings samples using X-ray diffraction techniques and visual observation confirmed all tomographic findings.  

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