Colloidal gold and silica in mesothermal vein systems

Abstract

Research Article| June 01, 1993 Colloidal gold and silica in mesothermal vein systems R. J. Herrington; R. J. Herrington 1Department of Mineralogy, Natural History Museum, London SW7 5BD, England Search for other works by this author on: GSW Google Scholar J. J. Wilkinson J. J. Wilkinson 2Department of Geology, Imperial College, London SW7 2BP, England Search for other works by this author on: GSW Google Scholar Author and Article Information R. J. Herrington 1Department of Mineralogy, Natural History Museum, London SW7 5BD, England J. J. Wilkinson 2Department of Geology, Imperial College, London SW7 2BP, England Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1993) 21 (6): 539–542. https://doi.org/10.1130/0091-7613(1993)021<0539:CGASIM>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation R. J. Herrington, J. J. Wilkinson; Colloidal gold and silica in mesothermal vein systems. Geology 1993;; 21 (6): 539–542. doi: https://doi.org/10.1130/0091-7613(1993)021<0539:CGASIM>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Some of the textural features of mesothermal gold-quartz veins may be best explained by the initial precipitation of amorphous silica gel (colloid), which subsequently crystallizes to quartz. This can occur in brittle-ductile shear zones where a significant fluid-pressure drop occurs during stick-slip failure. Such a process rapidly supersaturates the hydrothermal fluid with respect to amorphous silica, which precipitates instead of quartz, owing to favorable kinetics. Depressurization also commonly leads to fluid unmixing and destabilization of soluble gold complexes. However, the presence of colloidal silica can stabilize gold colloid, allowing further transport of particulate gold in suspension in the hydrothermal fluid. Silica gel would be highly unstable under mesothermal conditions and would undergo rapid syneresis and crystallization to form quartz; solid impurities would tend to be expelled toward grain boundaries. This model can account for the primary anhedral aggregate textures typical of mesothermal quartz veins, the concentration of gold along grain boundaries and the formation of discrete gold nuggets, and the rare occurrence of low-order silica polymorphs and relict spheroidal structures. The transport of gold in colloidal form may be one reason for the frequently consistent bulk grade distribution in gold-quartz vein systems over many hundreds of metres (in some cases kilometres) of depth. In addition, the formation of charged colloidal particles may help to explain the attraction of gold grains to specific mineral surfaces. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.