• 标题：Discovery of Gold Nanoparticles in Marcellus Shale
• 关键词：Gold nanoparticles;opal;colloid;shale;Marcellus Formation;and TEM
• 作者：

全文下载

A high density of gold (Au) nanoparticles has been observed on the surfaces of the coexisting opal nanospheres in kerogen-bearing shales from the Marcellus Formation. Our analyses of the Au nanoparticles and associated minerals indicate that this represents a new formation type of colloidal gold nanoparticles. Additionally, the opal nanospheres are a new kind of natural opal-A that is characteristic of the mesoporous texture formed through oil-in-water emulsion processes. High-resolution transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy analysis directly reveals spherical gold nanoparticles and gold nanorods associated with mesoporous opal nanospheres. Our newly found textures indicate that opal nanospheres may have facilitated the co-precipitation of pure gold nanoparticles in organic-bearing, reduced environments. Furthermore, our TEM observations provide distinct images of the initial phase of colloidal gold and silica, which may contribute to the formation of Au deposits involving “invisible” gold, secondary supergene enrichments, or high-grade gold accumulations. The discovery of Au nanoparticles in hydrocarbon-rich shale formations such as Marcellus (which contains 0.6–4.1 wt % gold/opal) suggests a potential for co-production of both gas/oil and gold—two valuable commodities.