Archaeological applications of natural gold analyses

2021 ◽  
pp. SP516-2021-59
Author(s):  
C. D. Standish ◽  
R. J. Chapman ◽  
N. R. Moles ◽  
R. D. Walshaw ◽  
J. A. Sheridan
Keyword(s):  
High Temperature ◽  
Bulk Alloy ◽  
Provenance Studies ◽  
Mineral Inclusions ◽  
Compositional Approach ◽  
Icp Ms ◽  
Wide Range ◽  
High Temperature Reactions ◽  
Microchemical Characterization

AbstractCompositional studies of natural gold usually have a geological focus, but are also important in archaeological provenancing. Both methodologies rely on compositional comparison of two sets of samples, one of which is geographically constrained. Here we describe how experiences in gold characterization resulting from geological studies are relevant to archaeology. Microchemical characterization of polished sections of natural gold identifies alloy compositions, alloy heterogeneity and mineral inclusions. Gold from all deposit types shows Cu and Sn values much lower than those recorded during numerous studies of artefacts. Inclusions in artefact gold include various Cu- and Sn-bearing compounds which indicate specific high temperature reactions that could ultimately illuminate the conditions of (s)melting. The use of LA-ICP-MS to generate a wide range of elemental discriminants for provenance studies may be compromised by alloy adulteration and/or unrepresentative analysis of natural/artefact alloys, which are commonly highly heterogeneous at the micron scale. Geological studies normally characterize only the earliest-formed (hypogene) alloy, whereas archaeology-focussed studies should entail analyses of bulk alloy compositions and impurities that may be incorporated during (s)melting. Isotopic-based provenancing alleviates many of these problems but, to date, generates regional rather than locality specific targets. A dual isotopic-compositional approach is recommended.

scholarly journals Characterization of the Heavy Mineral Suite in a Holocene Beach Placer, Barrytown, New Zealand

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 86
Author(s):  
Hannah C. Wells ◽  
Richard G. Haverkamp
Keyword(s):  
New Zealand ◽  
Heavy Minerals ◽  
Sem Images ◽  
Density Fractions ◽  
Icp Ms ◽  
Wide Range ◽  
Ore Minerals ◽  
Grain Size Distributions ◽  
Elemental Associations

The placer deposit at Barrytown, New Zealand, has been worked for gold and is known for high levels of ilmenite that has not been exploited. Other heavy minerals are present but have not been well characterized, which is the purpose of this research. Sand grains were separated into the density fractions and the heavier fractions analyzed by laser ablation ICP-MS for elemental composition and by scanning electron microscopy (SEM) EDS in whole grains and polished sections. Grain size distributions were determined from SEM images of polished grain mounts. Elemental associations have been identified with different minerals. A wide range of ore minerals, or potential useful industrial minerals, have been shown to be present largely as individual sand grains. These include gold, ilmenite, garnet, zircon, monazite, allanite, uraninite, thorite, cassiterite, wolframite, scheelite, and columbite. The ilmenite contains many inclusions, consisting of silicates and phosphates and 100–400 ppm Nb. Scandium is found to be present in zircon at 100–600 ppm along with 3000 ppm Y. Monazite is depleted in Eu relative to chondrite and contains Ga and Ge at 1000–3000 ppm. Because the sand grains are mostly individual minerals, it is suggested that separation may be possible using a combination of density, electrostatic and magnetic methods to obtain almost pure mineral fractions. This knowledge should inform decisions on potential exploitation of the resource.

scholarly journals Development of Analytical Procedures for Chemical Characterization of Substrates for the Production of TRISO Coated Particles as Nuclear Fuel in High Temperature Gas-Cooled Reactors

2020 ◽  
Vol 12 (17) ◽  
pp. 7221
Author(s):  
Ewelina Chajduk ◽  
Paweł Kalbarczyk ◽  
Jakub Dudek ◽  
Marta Pyszynska ◽  
Anna Bojanowska-Czajka ◽  
...  
Keyword(s):  
High Temperature ◽  
Nuclear Fuel ◽  
Inductively Coupled Plasma ◽  
Chemical Characterization ◽  
Quantitative Chemical Analysis ◽  
Coated Particles ◽  
Icp Ms ◽  
Analytical Procedures ◽  
High Temperature Gas

High temperature gas-cooled reactors have recently gained importance as a source of electricity and process heat. Nuclear fuel used in these reactors consists of TRISO (TRiple coated ISOtropic) coated particles, where spherical grains of UO2 or UC2 or UCO kernel are covered with four successive layers consisting of pyrolytic carbon and silicon carbide. Of great importance is the chemical purity of reagents and substances used for the production of TRISO coated fuel particles. Analytical techniques ensuring the determination of elements at trace levels are inductively coupled plasma mass spectrometry (ICP-MS) and neutron activation analysis (NAA). They were applied in this work for the chemical characterization of substrates used for TRISO fuel production. Two analytical procedures were developed: the first, where materials are analyzed using ICP-MS, and the second with the aid of NAA. Successive stages of these procedures are described with details. Results of quantitative chemical analysis of examined substances are reported as well as detection limits for the investigated elements. Moreover, the expanded uncertainties estimated for the determined elements while employing the devised analytical procedures are presented.

Use of two-color array pyrometry for characterization of combustion synthesis waves

2000 ◽  
Vol 15 (2) ◽  
pp. 572-580 ◽  
Author(s):  
U. Anselmi-Tamburini ◽  
F. Maglia ◽  
G. Spinolo ◽  
Z. A. Munir
Keyword(s):  
Activation Energy ◽  
Wave Propagation ◽  
High Temperature ◽  
Combustion Synthesis ◽  
Morphological Changes ◽  
Formation Of Cracks ◽  
High Temperature Reactions ◽  
Time Sequences

A two-color array pyrometer was used to investigate morphological developments on the surface of materials undergoing self-propagating high-temperature reactions. Time sequences of temperature spatial profiles during wave propagation were found to be complex in their nature and dynamics. They contain features that are interpreted in terms of morphological changes during the process. These features include formation of cracks or voids, expansion of the sample, and formation of droplets of metals on the surface. The use of the array pyrometer for determination of the activation energy of the combustion reaction between Zr and NiO is reported.

Characterization of High-Temperature Reactions at the BaO/W Interface

Langmuir ◽  
1996 ◽  
Vol 12 (21) ◽  
pp. 5099-5108 ◽  
Author(s):  
Jianou Shi ◽  
David L. Allara
Keyword(s):  
High Temperature ◽  
High Temperature Reactions

scholarly journals Coupled Zircon-Rutile U-Pb Chronology: LA ICP-MS Dating, Geological Significance and Applications to Sediment Provenance in the Eastern Himalayan-Indo-Burman Region

Geosciences ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 467 ◽  
Author(s):  
Laura Bracciali
Keyword(s):  
Thermal Evolution ◽  
Secondary Growth ◽  
Sediment Provenance ◽  
Good Precision ◽  
Combined Application ◽  
Geological Processes ◽  
Icp Ms ◽  
Wide Range ◽  
Isotopic Characterization

U-Pb dating by LA ICP-MS is one of the most popular and successful isotopic techniques available to the Earth Sciences to constrain timing and rates of geological processes thanks to its high spatial resolution, good precision (absolute U/Pb age resolution of ca. 2%, 2s), rapidity and relative affordability. The significant and continuous improvement of instrumentation and approaches has opened new fields of applications by extending the range of minerals that can be dated by this method. Following the development and distribution to the community of good quality reference materials in the last decade, rutile U-Pb thermochronology (with a precision only slightly worse than zircon) has become a commonly used method to track cooling of deep-seated rocks. Its sensitivity to mid- to low-crustal temperatures (~450 °C to 650 °C) is ideal to constrain exhumation in active and ancient orogens as well as thermal evolution of slow-cooled terranes. Recrystallization and secondary growth during metamorphism and the presence of grain boundary fluids can also affect the U-Pb isotopic system in rutile. A growing body of research focusing on U-Pb dating of rutile by LA ICP-MS is greatly improving our understanding of the behavior of this mineral with regards to retention of radiogenic Pb. This is key to fully exploit its potential as a tracker of geological processes. The latest developments in this field are reviewed in this contribution. The combined application of U-Pb zircon and rutile chronology in provenance studies, particularly when complemented by lower-T thermochronometry data, allows the isotopic characterization of the sources across a wide range of temperatures. The benefits of applying detrital zircon-rutile U-Pb chronology as a coupled provenance proxy are presented here, with a focus on the Eastern Himalayan-Indo-Burman region, where a growing number of successful studies employs such an approach to help constrain river drainage and basin evolution and to infer feedback relationships between erosion, tectonics and climate.

scholarly journals Study on thermophiles reveals the presence of Actinobacillus lignieresii in cattle compost

2013 ◽  
Vol 1 (2) ◽  
pp. 33-41 ◽  
Author(s):  
Gagandeep Singh Saggu ◽  
Divya Shrivastava
Keyword(s):  
High Temperature ◽  
16S Rrna ◽  
Extreme Condition ◽  
Biochemical Tests ◽  
Genus Level ◽  
Acceptable Range ◽  
Wide Range ◽  
Environment Condition ◽  
Important Activity

Introduction- Moderate environment is important to sustain life any environment condition that can be perceived as beyond the normal acceptable range is extreme condition and if we are talking in the terms of temperature than its called thermophillic environment.Aim & objective- The study was designed to study the diversity of thermophiles present in compost and characterization of the properties which are responsible for their adequate nature to sustain high temperature. Material and method- Microorganisms were isolated from cattle compost and initially screened by biochemical tests to characterize till genus level. Confirmation of Actinobacillus spp. was done by fermentation reactions of nine carbohydrates and amplification of 16S rRNA region. Results- Isolates from compost showed wide range of growth temperatures which suggest their important activity during the whole composting process. This study initially designed to study the diversity of thermophiles in compost which turned specifically to A. lignieresii.DOI: http://dx.doi.org/10.3126/ijasbt.v1i2.8200 Int J Appl Sci Biotechnol, Vol. 1(2): 33-41

Characterization of Dynamic Globularization Behavior during Hot Working of Ti-6Al-4V Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 1033-1036 ◽  
Author(s):  
Jong Taek Yeom ◽  
Jeoung Han Kim ◽  
Nam Yong Kim ◽  
Nho Kwang Park ◽  
Chong Soo Lee
Keyword(s):  
High Temperature ◽  
Microstructure Evolution ◽  
True Strain ◽  
Hot Working ◽  
Strain Rates ◽  
Flow Curves ◽  
Deformation Parameters ◽  
Wide Range ◽  
Lamellae Structure

The dynamic globularization behavior during hot working of Ti-6Al-4V alloy was investigated by high temperature torsion tests. The torsion tests were carried out to investigate microstructure evolution occurring during dynamic globularization in Ti-6Al-4V alloy. The torsion tests were performed under a wide range of temperatures and strain rates with true strain up to 2. The flow curves revealed that the amount of flow softening for the fine alpha-lamellae structure was higher than that for the coarse alpha-lamellae structure under the temperature of 900oC. The effects of hot deformation parameters and initial microstructures on the dynamic globularization were analyzed.

scholarly journals Circuit Techniques in GaN Technology for High-Temperature Environments

Electronics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 42
Author(s):  
Ahmad Hassan ◽  
Jean-Paul Noël ◽  
Yvon Savaria ◽  
Mohamad Sawan
Keyword(s):  
High Temperature ◽  
Integrated Circuits ◽  
National Research Council ◽  
Logic Gates ◽  
Voltage Reference ◽  
Flip Flop ◽  
Wide Range ◽  
Circuit Techniques ◽  
First Time

As a wide bandgap semiconductor, Gallium Nitride (GaN) device proves itself as a suitable candidate to implement high temperature (HT) integrated circuits. GaN500 is a technology available from the National Research Council of Canada to serve RF applications. However, this technology has the potential to boost HT electronics to higher ranges of operating temperatures and to higher levels of integration. This paper summarizes the outcome of five years of research investigating the implementation of GaN500-based circuits to support HT applications such as aerospace missions and deep earth drilling. More than 15 integrated circuits were implemented and tested. We performed the HT characterization of passive elements integrated in GaN500 including resistors, capacitors, and inductors up to 600 °C. Moreover, we developed for the first time several digital circuits based on GaN500 technology, including logic gates (NOT, NAND, NOR), ring oscillators, D Flip-Flop, Delay circuits, and voltage reference circuits. The tested circuits are fabricated on a 4 mm × 4 mm chip to validate their functionality over a wide range of temperatures. The logic gates show functionality at HT over 400 °C, while the voltage reference circuits remain stable up to 550 °C.

Precursors to Boron-Nitrogen Macromolecules and Ceramics

1986 ◽  
Vol 73 ◽  
Author(s):  
C. K. Narula ◽  
R. T. Paine ◽  
R. Schaeffer
Keyword(s):  
High Temperature ◽  
Boron Nitride ◽  
Important Material ◽  
The Past ◽  
High Temperature Reactions ◽  
Boron Nitrogen

ABSTRACTBoron nitride has been prepared in the past from classical high temperature reactions and more recently by CVD methods. Few attempts have been made to prepare this important material from pyrolyses of preceramic oligomers or polymers. In the present study oligomerization reactions of substituted borazenes with silyamine crosslinking groups have been found to provide useful gel materials which upon pyrolysis form boron nitrogen materials. Selected aspects of this chemistry and some characterization of the materials is presented.

Sign in / Sign up

Export Citation Format

Share Document