Next Article in Journal
Rheology of Fly Ash Mixed Tailings Slurries and Applicability of Prediction Models
Next Article in Special Issue
Muscovite 40Ar/39Ar Age and H-O-S Isotopes of the Shimensi Tungsten Deposit (Northern Jiangxi Province, South China) and Their Metallogenic Implications
Previous Article in Journal
Mineral Quantification with Simultaneous Refinement of Ca-Mg Carbonates Non-Stoichiometry by X-ray Diffraction, Rietveld Method
Previous Article in Special Issue
Contrasting Surficial Composition of Native Gold from Two Different Types of Gold Ore Deposits
Article Menu
Issue 9 (September) cover image

Export Article

Open AccessReview
Minerals 2017, 7(9), 163; doi:10.3390/min7090163

Formation and Aggregation of Gold (Electrum) Nanoparticles in Epithermal Ores

1
Department of Geosciences, Auburn University, Auburn, AL 36849, USA
2
Department of Geology and Environmental Earth Science, Miami University, Oxford, OH 45056, USA
*
Author to whom correspondence should be addressed.
Received: 10 August 2017 / Revised: 31 August 2017 / Accepted: 6 September 2017 / Published: 8 September 2017
(This article belongs to the Special Issue Geochemistry and Mineralogy of Hydrothermal Metallic Mineral Deposits)
View Full-Text   |   Download PDF [3818 KB, uploaded 8 September 2017]   |  

Abstract

Here, we review the concept that nanoparticles and colloids may have played a significant role in forming some types of hydrothermal ores deposits, particularly epithermal. This concept was first proposed almost a century ago but the development of new analytical technologies, lab experiments, and the discovery of new epithermal deposits where nanoparticles are evident have added credence to the “gold colloid theory”. Nanoparticles are defined to have at least one dimension <10−7 m, and may have different chemical and physical properties than the bulk solids. Colloids are typically <10−6 m in diameter and have the added characteristic that they are dispersed in another medium. In epithermal ore-forming solutions, gold or electrum nanoparticles nucleate from supersaturated hydrothermal solutions, and thus this is a “far-from-equilibrium” process. In some cases, gold nanoparticles may simply play a transitory role of aggregating to form much coarser-grained crystals, where all of the evidence of nanoparticles precursor phases is not preserved. However, in some epithermal ores, silica nanoparticles also formed, and their co-deposition with gold (electrum) nanoparticles preserved the gold aggregation features as self-organized “fractal” dendrites. Here, we review existing the data on gold and electrum nanoparticles in epithermal ores, present images of electrum nanoparticles and their aggregates, and discuss the significance of gold nanoparticles formation and aggregation in helping to produce some of the highest-grade gold ores in the world. View Full-Text
Keywords: gold nanoparticles; colloids; epithermal ores; aggregation gold nanoparticles; colloids; epithermal ores; aggregation
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Saunders, J.A.; Burke, M. Formation and Aggregation of Gold (Electrum) Nanoparticles in Epithermal Ores. Minerals 2017, 7, 163.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Minerals EISSN 2075-163X Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top