Hallis, L.J.

Kovacs, A.

Lee, M.R.

MacLaren, I.

Mark, D.

Smith, C.L.

Tomkinson, T.

English

Enlighten: Publications

n 
 
 
 
 
 
 
Lee, M.R., MacLaren, I., Kovacs, A., Tomkinson, T., Mark, D., Hallis, L.J., 
and Smith, C.L. (2014) Coated silica nanoparticles in Nakhla iddingsite 
veins: implications for waterrock interaction within the Martian crust. In: 
77th Annual Meeting of the Meteoritical Society, 8-13 September 2014, 
Casablanca, Morocco. 
 
 
Copyright © 2014 The Authors 
  
 
 
http://eprints.gla.ac.uk/97470/  
 
 
 
 
 
Deposited on:  25 September 2014 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Enlighten – Research publications by members of the University of Glasgow 
http://eprints.gla.ac.uk 
COATED SILICA NANOPARTICLES IN NAKHLA 
IDDINGSITE VEINS: IMPLICATIONS FOR WATER-
ROCK INTERACTION WITHIN THE MARTIAN CRUST.  
M. R. Lee1, I. MacLaren2, A. Kovacs3, T. Tomkinson1,4, D. F. 
Mark4, L. J. Hallis1 & C. L. Smith5. 1School of Geographical & 
Earth Sciences, University of Glasgow, G12 8QQ, UK 
Martin.Lee@Glasgow.ac.uk. 2School of Physics & Astronomy, 
University of Glasgow, G12 8QQ, UK 3Ernst Ruska-Centrum für 
Mikroskopie und Spektroskopie mit Elektronen, 
Forschungszentrum Jülich GmbH, 52425 Jülich, Germany. 
4Scottish Universities Environmental Research Center, East 
Kilbride, UK 5Natural History Museum, London, SW7 5BD, UK  
 
Introduction: Nakhla is a martian olivine-bearing 
clinopyroxenite fall that contains 0.11-0.13 wt. % water [1, 2]. 
Most of this water is contained within olivine-hosted veins of 
‘iddingsite’, whose principal constituent is a Mg- and Fe-bearing 
hydrous silicate [3]. Since the discovery of iddingsite in 1975 [4], 
the Mg-Fe silicate has proven difficult to identify, largely owing 
to its very fine grain size. Findings from examination of this ma-
terial by transmission electron microscopy (TEM) are contradic-
tory, and include: smectite [3]; smectite plus hematite, goethite, 
quartz, cristobalite, tridymite and amorphous silica [5]; amor-
phous gel [6]. We have sought to resolve this debate by high-
resolution electron imaging and spectroscopy of Nakhla 
iddingsite veins. 
Methods: Using a FEI Duomill focused ion beam instru-
ment, an electron transparent foil was cut from a vein in a pol-
ished thin section prepared from Nakhla BM1913,25. The foil 
was milled initially to ~100 nm and then further thinned to ~50 
nm by argon ion milling using a Fischione Nanomill operated at 
500 eV. (Scanning) TEM was performed using a JEOL 
ARM200F including electron energy loss spectroscopy (EELS) 
with a Gatan GIF Quantum. EELS was used to map chemical 
compositions and Fe valence states at nanometre resolution. 
Results and discussion: We focused on an iddingsite vein 
containing a central band of Mg-Fe silicate that is flanked by si-
derite, itself partially altered to goethite. The Mg-Fe silicate 
yields diffraction rings with d-spacings of 0.254 and 0.154 nm, 
and dark-field TEM imaging using the 0.254 nm ring demon-
strates that it is formed by scattering from numerous ~2-5 nm 
sized crystals. STEM imaging and EELS mapping shows a struc-
ture of globular nanoparticles embedded in a matrix; most of the 
nanoparticles are 3-5 nm in diameter, although a small proportion 
are larger, up to 30 nm. The nanoparticles are almost pure silica, 
and the O- Mg- and Fe3+-rich composition of their matrix is con-
sistent with a ferrihydrite/goethite coating, probably intergrown 
with smectite. Our discovery of embedded silica nanoparticles 
agrees well with previous mineral identifications by Thomas-
Keptra et al. [5]. Nakhla vein formation started by dissolution of 
olivine [7], and the challenge now is to determine why this reac-
tion produced nanoparticles, and the implications of their discov-
ery for understanding water-rock interaction within crust of Mars. 
References: [1] Karlsson H. R. et al., 1992. Science 
255:1409–1411. [2] Leshin L. A. et al. 1996. Geochmica et 
Cosmochimica Acta 60:2635-2650. [3] Gooding J. L. et al. 1991. 
Meteoritics 26:135–143. [4] Ashworth J. R. and Hutchison R. 
1975. Nature 256:714–715. [5] Thomas-Keptra, K. L. et al. 2000. 
Abstract #1690. 31st Lunar & Planetary Science Conference. [6] 
Changela H. G. and Bridges J. C. 2011. Meteoritics & Planetary 
Science 45:1847–1867. [7] Lee M. R. et al. 2013. Meteoritics & 
Planetary Science 48:224–240. 
5214.pdf77th Annual Meteoritical Society Meeting (2014)


Coated silica nanoparticles in Nakhla iddingsite veins: implications for waterrock interaction within the Martian crust

Silica nanoparticles coated with iron hydroxide and smectite are a major constituent of ‘iddingsite’ veins in the Nakhla meteorite. This unexpected discovery has important implications for understanding water-rock interaction in the martian crust

Lee, Martin R.

Mark, D. F.

Hallis, L.

Smith, C. L.

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Coated Silica Nanoparticles in Nakhla Iddingsite Veins:Implications for Water-Rock Interaction Within the Martian Crust

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n       Lee, M.R., MacLaren, I., Kovacs, A., Tomkinson, T., Mark, D., Hallis, L.J., and Smith, C.L. (2014) Coated silica nanoparticles in Nakhla iddingsite veins: implications for waterrock interaction within the Martian crust. In: 77th Annual Meeting of the Meteoritical Society, 8-13 September 2014, Casablanca, Morocco.   Copyright © 2014 The Authors     http://eprints.gla.ac.uk/97470/       Deposited on:  25 September 2014                   Enlighten – Research publications by members of the University of Glasgow http://eprints.gla.ac.uk COATED SILICA NANOPARTICLES IN NAKHLA IDDINGSITE VEINS: IMPLICATIONS FOR WATER-ROCK INTERACTION WITHIN THE MARTIAN CRUST.  M. R. Lee1, I. MacLaren2, A. Kovacs3, T. Tomkinson1,4, D. F. Mark4, L. J. Hallis1 & C. L. Smith5. 1School of Geographical & Earth Sciences, University of Glasgow, G12 8QQ, UK Martin.Lee@Glasgow.ac.uk. 2School of Physics & Astronomy, University of Glasgow, G12 8QQ, UK 3Ernst Ruska-Centrum für Mikroskopie und Spektroskopie mit Elektronen, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany. 4Scottish Universities Environmental Research Center, East Kilbride, UK 5Natural History Museum, London, SW7 5BD, UK   Introduction: Nakhla is a martian olivine-bearing clinopyroxenite fall that contains 0.11-0.13 wt. % water [1, 2]. Most of this water is contained within olivine-hosted veins of ‘iddingsite’, whose principal constituent is a Mg- and Fe-bearing hydrous silicate [3]. Since the discovery of iddingsite in 1975 [4], the Mg-Fe silicate has proven difficult to identify, largely owing to its very fine grain size. Findings from examination of this ma-terial by transmission electron microscopy (TEM) are contradic-tory, and include: smectite [3]; smectite plus hematite, goethite, quartz, cristobalite, tridymite and amorphous silica [5]; amor-phous gel [6]. We have sought to resolve this debate by high-resolution electron imaging and spectroscopy of Nakhla iddingsite veins. Methods: Using a FEI Duomill focused ion beam instru-ment, an electron transparent foil was cut from a vein in a pol-ished thin section prepared from Nakhla BM1913,25. The foil was milled initially to ~100 nm and then further thinned to ~50 nm by argon ion milling using a Fischione Nanomill operated at 500 eV. (Scanning) TEM was performed using a JEOL ARM200F including electron energy loss spectroscopy (EELS) with a Gatan GIF Quantum. EELS was used to map chemical compositions and Fe valence states at nanometre resolution. Results and discussion: We focused on an iddingsite vein containing a central band of Mg-Fe silicate that is flanked by si-derite, itself partially altered to goethite. The Mg-Fe silicate yields diffraction rings with d-spacings of 0.254 and 0.154 nm, and dark-field TEM imaging using the 0.254 nm ring demon-strates that it is formed by scattering from numerous ~2-5 nm sized crystals. STEM imaging and EELS mapping shows a struc-ture of globular nanoparticles embedded in a matrix; most of the nanoparticles are 3-5 nm in diameter, although a small proportion are larger, up to 30 nm. The nanoparticles are almost pure silica, and the O- Mg- and Fe3+-rich composition of their matrix is con-sistent with a ferrihydrite/goethite coating, probably intergrown with smectite. Our discovery of embedded silica nanoparticles agrees well with previous mineral identifications by Thomas-Keptra et al. [5]. Nakhla vein formation started by dissolution of olivine [7], and the challenge now is to determine why this reac-tion produced nanoparticles, and the implications of their discov-ery for understanding water-rock interaction within crust of Mars. References: [1] Karlsson H. R. et al., 1992. Science 255:1409–1411. [2] Leshin L. A. et al. 1996. Geochmica et Cosmochimica Acta 60:2635-2650. [3] Gooding J. L. et al. 1991. Meteoritics 26:135–143. [4] Ashworth J. R. and Hutchison R. 1975. Nature 256:714–715. [5] Thomas-Keptra, K. L. et al. 2000. Abstract #1690. 31st Lunar & Planetary Science Conference. [6] Changela H. G. and Bridges J. C. 2011. Meteoritics & Planetary Science 45:1847–1867. [7] Lee M. R. et al. 2013. Meteoritics & Planetary Science 48:224–240. 5214.pdf77th Annual Meteoritical Society Meeting (2014)

http://eprints.gla.ac.uk/97470/1/97470.pdf

Coated silica nanoparticles in Nakhla iddingsite veins: implications for waterrock interaction within the Martian crust

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