干旱区生态环境知识资源中心(Arid): Nanoscale structure and compositional analysis of manganese oxide coatings on the Smithsonian Castle, Washington, DC

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DOI	10.1016/j.chemgeo.2020.119486
	Nanoscale structure and compositional analysis of manganese oxide coatings on the Smithsonian Castle, Washington, DC
	Sharps, Meredith C.1,2; Grissom, Carol A.2; Vicenzi, Edward P.2
通讯作者	Vicenzi, Edward P.
来源期刊	CHEMICAL GEOLOGY
ISSN	0009-2541
EISSN	1872-6836
出版年	2020
卷号	537
英文摘要	The Smithsonian Castle is a historic building in Washington, D.C. that was erected 165 years ago and served as the first home for the Smithsonian Institution. Currently, the building exhibits dark surface discoloration due to manganese-rich coatings that are growing in patches across its Seneca sandstone exterior. Bulk and microanalysis of this coating indicate that it is consistent with rock varnish, but the coating is difficult to analyze without contribution from the underlying minerals that comprise the sandstone. To address this limitation, SEM/FIB-prepared cross-sections of the coating were analyzed using HRTEM, STEM-EDX, and SAED analyses in order to study the nanoscale structure and composition of the Mn-rich coating in isolation, without convolution from the sandstone. Structurally, the coating is < 1 mu m thick, polycrystalline, and composed primarily of birnessite, a layered manganese oxide. High spatial resolution data reveal that the coating is Ca-bearing, with only minor quantities of Fe, Si, and Al, distinguishing it compositionally from typical manganese rock varnish and classifying it instead as a manganese skin. TEM revealed layers of aeolian detritus below and a thin silica glaze above the Mn-rich coating, providing a relative timeline of formation. Nanoscale particulates of barite found within the Mn-rich coating, along with the micro- and nanoscale detritus below the coating, indicate atmospheric deposition as the main source for both Mn and Ba. The compositional and structural information gathered from these analyses helps constrain mechanisms of formation towards a biological origin; however, no direct evidence for Mn oxide producing microorganisms was observed.
英文关键词	Rock varnish Manganese oxide Metal skin Birnessite Microanalysis Microstructure
类型	Article
语种	英语
国家	USA
开放获取类型	Bronze
收录类别	SCI-E
WOS记录号	WOS:000518383000011
WOS关键词	ROCK-VARNISH ; DESERT VARNISH ; ELEMENT CHEMISTRY ; MINERALOGY ; GROWTH ; BIRNESSITE ; DENDRITES ; OXIDATION ; BACTERIA ; DEPOSITS
WOS类目	Geochemistry & Geophysics
WOS研究方向	Geochemistry & Geophysics
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/314249
作者单位	1.Univ Oregon, Dept Chem & Biochem, Eugene, OR 97403 USA; 2.Smithsonian Inst, Museum Conservat Inst, 4210 Silver Hill Rd, Suitland, MD 20746 USA
推荐引用方式 GB/T 7714	Sharps, Meredith C.,Grissom, Carol A.,Vicenzi, Edward P.. Nanoscale structure and compositional analysis of manganese oxide coatings on the Smithsonian Castle, Washington, DC[J],2020,537.
APA	Sharps, Meredith C.,Grissom, Carol A.,&Vicenzi, Edward P..(2020).Nanoscale structure and compositional analysis of manganese oxide coatings on the Smithsonian Castle, Washington, DC.CHEMICAL GEOLOGY,537.
MLA	Sharps, Meredith C.,et al."Nanoscale structure and compositional analysis of manganese oxide coatings on the Smithsonian Castle, Washington, DC".CHEMICAL GEOLOGY 537(2020).