Mineral Spectroscopy Theory - PowerPoint Presentation

1. Mineral Spectroscopy TheoryCarsten Laukamp, CSIRO Mineral Resources

2. crushing,grinding,sieving,filtering,…fresh surface“peel”(weathered surface)GeochemistryMineral Spectroscopy2 |Mineral Spectroscopy Theory

3. refractionreflection3 |Mineral Spectroscopy Theory Scattering effects Volume and / or surface scattering Single or multiple volume scattering Diffuse and / or specular reflection Refractive index (real)

4. Wavelength regionsMineral Spectroscopy Theory4 |Ramanaidou et al. (2015)

5. Absorption in VNIR &SWIR mainly due to: Electronic and / or Vibrational processes5 |Mineral Spectroscopy Theory

6. Spectral-Mineral Wavelength RegionsFrom Peter HausknechtVNIRiron oxidesREEsvegetationSWIROH-bearing hydroxyls(kaolin, chlorite, mica, amphibole) sulphatescarbonatesTIRNon-OH-bearing silicates(quartz, feldspars, pyroxene, garnet)sulphatescarbonates6 |Mineral Spectroscopy Theory

7. Affects on Spectral Behaviour1. Mineralogy2. Cation Composition3. Crystallinity (disorder)4. Water (free, adsorbed, absorbed, structural)5. Particle size6. Orientation 7. Mixtures8. Organic matter7 |Mineral Spectroscopy Theory

8. Electronic ProcessesInvolve the transfer of electrons from lower to higher energy states within electron orbits (crystal field) or from the ligand to the cation (charge transfer)Mineral Spectroscopy TheoryCudahy & Ramanaidou (1997)8 |

9. VNIR SpectraCrystal fieldCrystal fieldcalcitemuscovitekaolinitehematitejarositeferrihydritelimonitegoethiteactinoliteCharge transfer absorptionVNIR spectra of iron-oxide bearing minerals vs. other major rock forming mineralsFe2+Fe3+OHFe3+0.840.90 - 0.920.904 - 0.920.86 - 0.92Crystal fieldElectronic processes: Involve the transfer of electrons from lower to higher energy states within electron orbits (crystal field) or from the ligand to the cation (charge transfer)VNIRSWIR9 |Mineral Spectroscopy Theory

10. Vitreous and ochreous goethiteVitreous goethiteOchreous goethiteCourtesy of Maarten Haest10 |Mineral Spectroscopy Theory

11. 11 |Rowan et al. (1986)Locations of REE absorption features:Nd: 420, 475, 525, 580, 740, 800, 870 Sm: ca. 920, 1090, 1250Pr: ca. 595, ca. 1000Eu: ca. 470, ca. 540Water-related featuresREE-bearing VNIR SpectraElectronic absorption processes in trivalent REE lead to sharp absorption features in the visible to near infrared wavelength region (ca. 400 to 1100 nm) (Fassel, 1961).Three of the fourteen REE oxides don’t show these because of their electronic configuration: La2O3, Lu2O3 and CeO3 (White, 1967).In high albedo samples, detection limit for Nd: 300 ppm (Rowan et al., 1986).Electronic absorption bands of ferric iron in iron oxides may partially mask REE-related absorption features (Rowan et al., 1986).Mineral Spectroscopy Theory

12. 12 |Mineral Spectroscopy Theory

13. 13 |Mineral Spectroscopy Theory

14. Spectral signatures of rock-forming mineralsMineral Spectroscopy Theory14 |Ramanaidou et al. (accepted)

15. Spectral-Mineral Wavelength RegionsFrom Peter HausknechtVNIRiron oxidesREEsvegetationSWIROH-bearing hydroxyls(kaolin, chlorite, mica, amphibole) sulphatescarbonatesTIRNon-OH-bearing silicates(quartz, feldspars, pyroxene, garnet)sulphatescarbonates15 |Mineral Spectroscopy Theory

16. SWIR spectra - Hydroxyl Mineral GroupsAl(OH) 2170 - 2210 nmTopaz, Pyrophyllite, Kaolinite, Montmorillonite, Muscovite, Illite“Fe(OH)” 2250 - 2300 nmJarosite, Nontronite, Saponite, Hectorite“Mg(OH)” 2300 - 2400 nmChlorite, Talc, Epidote, Amphibole, Antigorite, Biotite, PhlogopiteSi(OH) 2240 nm (broad)Opaline silicaSWIR & TIRVibrational processes related to OH (consider location of OH group and occupation of cation sites! e.g. di-octahedral and tri-octahedral)Fundamental stretching (2700 - 3000 nm region)Fundamental bending (9000 - 11000 nm region)Overtone and combination tones (SWIR active)1400 nm feature (1st overtone of OH fundamental stretching vibration)2000-2500 nm features (combination of stretching and bending vibrations)16 |Mineral Spectroscopy Theory

17. Al(OH) Mineral Spectra(n+d) Al2OH17 |Mineral Spectroscopy Theory

18. Al-OH (Kaolin) SpectraDifferent 1400 nm doublet spacingsDifferent absorption geometry between 2160 and 2210 nm2n Al2OH(n+d) Al2OHMineral Spectroscopy Theory

19. CrystallinityOrdered versus disordered kaolin group mineralsMore ordered samples produce stronger, sharper absorptions: doublets are more sharply definedThe Hinckley IndexOther Kaolin family variations (Halloysite, Kaolinite, Dickite)Ordered versus disordered illite / muscovites 1M, 2M & 2T illites19 |Mineral Spectroscopy Theory

20. Kaolinite Hinckley Index Series20 |Mineral Spectroscopy TheoryCudahy (1997)

21. Kaolin GroupKaoliniteMineral Spectroscopy Theoryn+d(OH)o2206 nm2159, 2169, 2180 nmLaukamp et al. (2013)n+dAl-O-H bound vs. unbound H2O2nAl-O-H n+d(OH)i21 |Al2Si2O5(OH)4crystallinitypolymorphismKaolinite (well crystalline)

22. VWell-ordered kaolinitePoorly-ordered kaoliniteWell-ordered kaolinitePoorly-ordered kaoliniteHeight exaggeration: 12*Mineral Spectroscopy Theory22 |From Maarten Haest (2012)Application 1: transported vs in situRocklea Dome CID

23. Application 2: SWIR for mapping hydrothermal alterationMineral Spectroscopy TheoryQuartz-Alunite Epithermal systems, modified after Tosdal et al. (2009 )montmorilloniteillitechloritehalloysitekaoliniteepidotealuniteUSGS Spectral Libraryproximal - - - - - distal23 |/dickite +

24. Mineral chemistryOH stretching motion (n)OH bending motion (d)OH vibrations in phyllosilicates (modified after Bishop et al., 2008) vibrational frequency depends on cation occuping octahedral sites (M) coordination of the crystal influences OH vibration (i.e. dioctahedral = 2 M-sites filled vs. trioctahedral = all M-sites filled)SWIR: combination of n(OH) + d(OH)montmorilloniteillitechloritehalloysitekaoliniten+dAl-O-H unbound H2O2nAl-O-H epidotealuniten+dM-O-H 2nM-O-H USGS Spectral LibraryMineral Spectroscopy Theory24 |

25. SWIR Absorptions related to vibration of octahedrally coordinated atoms (Al3+, Fe2+, Fe3+, Ca2+, Mg2+, Cr3+, Ti4+, vacancies)Tschermak substitution (e.g. white micas)Tetrahedral Si4+ for Al3+Octahedral Mg2+ or Fe2+ for Al3+ Cation substitution (Al, Fe and Mg) in chlorite, biotite, phlogopite, amphibole, ...Mg number (Fe:Mg ratio) K vs Na vs Cainterlayer cations in phyllosilicates < SWIR sulphates < SWIR25 |Mineral Spectroscopy TheoryMineral Chemistry - SWIR

26. Chlorite SWIR Spectra26 |Mineral Spectroscopy Theory

27. Chlorite Cation Composition23602350234023302320Kleppe et al (2003)Spear, F.S. (1993)27 |Mineral Spectroscopy TheoryKleppe et al. (2003)

28. “””Mg(OH)””” Mineral Spectra“Mg(OH)” Mineral Spectra28 |Mineral Spectroscopy Theory

29. White Mica Chemistry MuscovitePhengite(Mg,Fe)oct Sitet = Aloct Al tetScott and Yang (1997)mineralminers.com/html/musmins.stm Al, Fe, Mg, Cr, VSi, AlK, Na, Caoctahedraltetrahedralinterlayer29 |Mineral Spectroscopy Theory

30. White mica chemistryChallenge - What can be done and what can’t!AlVI ↔ Fe, Mg, Cr, VAlIV ↔ SiK, Na, CaoctahedraltetrahedralinterlayerWhite mica chemistry – Al-rich (e.g. ms/par) vs. Al-poor micas (e.g. phengite)Sodic (e.g. par) vs. potassic micas (e.g. ms)? - Sorry, but no! (e.g. Martinez-Alonso et al., 2002)30 |Mineral Spectroscopy Theory

31. Sulphates31 |Mineral Spectroscopy TheoryBishop & Murad (2005)Bishop & Murad (2005)n+d(O-H)d(H2O)2n3(SO4)2-, 2d(OH)2n(O-H), n+2d(H2O)1760nm~6000nmca. 4500 to 5000nm~1480nm{Na/(Na+K)

32. Sulphate Mineral SpectraOHAlOHOHAlOHFeOHH2OH2OH2O32 |Mineral Spectroscopy Theory

33. Si(OH) Mineral Spectra2240 nm33 |Mineral Spectroscopy Theory

34. Carbonate SWIR Spectra - I2300-2400 nmIron absorptionVariable CO3 absorption34 |Mineral Spectroscopy Theory

35. Carbonate SWIR Spectra - IIMgCa35 |Mineral Spectroscopy Theory

36. 2300-2400 nmIron absorptionVariable CO3 absorption36 |Mineral Spectroscopy TheoryCarbonatesSWIRTIRRamanaidou et al. (accepted)

37. Feldspar TIR Reflectance Spectraalkaliplagioclase37 |Mineral Spectroscopy Theory

38. Silicate TIR Reflectance Spectra38 |Mineral Spectroscopy TheoryQuartzMicroclineHornblendeMuscoviteAlmandineFayaliteChloriteHedenbergite

39. TIR-indices vs. Geochem of igneous rocksAcidicIntermediateBasicUltrabasicBasaltBasaltic AndesineDaciteRhyoliteCF : SCFM (SiO2/(SiO2+MgO+FeOtot+CaO))Christiansen FeatureSCFMQuartzFeldsparPyroxenePD03 (TiO2 3.82 )MM03A (TiO2 0.63)Salisbury & Walter (1989); Iglesias et al. (2013)(coloured dots: FTIR)(whole rock geochem)39 |Mineral Spectroscopy Theory

40. Water EffectsWater is SWIR active (not VNIR)Water is a blackbody in TIRMajor water absorptions at 1450, 1920, 2700 and 7000 nmMajor ramp down from 1000 - 2700 nm Samples should therefore be “dry”Different types of water can be spectrally measuredHydrous species (eg. Smectites)40 |Mineral Spectroscopy Theory

41. SWIR Water Spectrum41 |Mineral Spectroscopy Theoryunbound water

42. Dry and Wet Cracow Kaolinite42 |Mineral Spectroscopy Theory

43. Particle Size EffectsRock versus powder measurementsGenerally smaller particle size (powders) yields brighter spectraPowders produce relatively weaker absorptions due to greater surface scattering and less volume scatteringNot all minerals react to grain size effects in the same way or to the same degreevolume (multiple/single) scatteringabsorption coefficient (opaque/transparent)43 |Mineral Spectroscopy Theory

44. Mineral Mixture Effects Linear mixturesmagnitude of spectral features correlated with abundancesingle scattering (e.g. many clays)Non-linear mixturesMagnitude of spectral features correlated non-linearly with abundance (e.g. carbonates)multiple scatteringcontrasting absorption coefficients (opaques and transparent materials like sulphides mixed with carbonates/quartz/mica/chlorite).44 |Mineral Spectroscopy Theory

45. Non linear mixing45 |Mineral Spectroscopy TheoryKing et al. (2004)

46. SWIR functional groups of major rock forming minerals (Laukamp, 2010)Mineral Spectroscopy Theory46 |

47. Spectral LibrariesMineral Spectroscopy Theory47 |USGS http://speclab.cr.usgs.gov/spectral.lib06/ds231/datatable.htmlJPL http://speclib.asu.edu/libmaker.phpASU http://speclib.jpl.nasa.gov/search-1/mineralRRUFF http://rruff.info/CSIRO currently only accessible in The Spectral Geologist software...

48. TIR SLMineral Spectroscopy Theory48 |ASDXRDFTIREPMA

49. Thank youCSIRO Mineral Resources FlagshipCarsten LaukampGeoscientistt +61 8 6436 8754e carsten.laukamp@csiro.auw http://c3dmm.csiro.au/

50. ReferencesCudahy, T. & Ramanaidou, E.R., 1997. Measurement of the hematite:goethite ratio using field visible and near-infrared reflectance spectrometry in channel iron deposits, Western Australia: Australian Journal of Earth Sciences, v. 44, p. 411−420.Cudahy, T.J., Caccetta, M., Cornelius, A., Hewson, R., Wells, M., Skwarnecki, M., Halley, S., Hausknecht, P., Mason, P., Quigley, M., 2005. Regolith, geology and alteration mineral maps from new generation airborne and satellite remote sensing technologies.- MERIWA Project M370, Report 252, 126 pages.Cudahy, T., Jones, M., Thomas, M., Laukamp, C., Caccetta, M., Hewson, R., Rodger, A., Verrall, M., 2008. Next generation mineral mapping: Queensland airborne HyMap and satellite ASTER surveys 2006–2008. CSIRO, p. 161.Iglesias, M.L., Laukamp, C., Alves Rolim, S.B., Barros Binotto, R. (accepted): Thermal Infrared Spectroscopy and Geochemical Analyses of Volcanic Rocks from the Paraná Basin (Brazil).- 13th International Congress of the Brazilian Geophysical Society & EXPOGEf, 26.-29. August 2013, Rio de Janeiro, Brazil, 4pp.Jakubec, J., 2004. Role of geology in diamond project development.- Lithos, 76, 337-345.King, P.L., Ramsey, M.S., Swayze, G.A., 2004. Infrared Spectroscopy in Geochemistry, Exploration Geochemistry, and Remote Sensing. Mineralogical Association of Canada.Kleppe, A.K., Jephcoat, A.P., Welch, M.D., 2003. The effect of pressure upon hydrogen bonding in chlorite: A Raman spectroscopic study of clinochlore to 26.5 Gpa. American Mineralogist, 88, 567-573.Laukamp, C., Termin, K.A., Pejcic, B., Haest, M., Cudahy, T., 2012. Vibrational spectroscopy of calcic amphiboles - applications for exploration and mining. European Journal of Mineralogy 24, 863-878.Scott, K., Yang, K., 1997. Spectral Reflectance Studies of white micas. CSIRO Exploration and Mining Report, 439R, 41 pages.Spear, F. S., 1993, Metamorphic Phase Equilibria and Pressure-Temperature-Time Paths, Mineralogical Society of America.Hecker, C., van der Meijde, M., van der Meer, F., 2010. Thermal infrared spectroscopy on feldspars – Successes, limitations and their implications for remote sensing.Mineral Spectroscopy Theory50 |

51. Additional Slides51 |Mineral Spectroscopy Theory

52. ReflectanceAbsorbanceSi-O bendingM-O stretchingSi-O stretchingν(Si-O)OH stretchingν(OH)ν(OH)+δ(OH)OH-bendingδ(OH)2 * ν(OH)4315, 43582.295, 2.317  2.32041992.38036742.72684, 64114.62, 15.6052519.0573481.36[cm-1][m]Tremolite Ca2Mg5Si2O22(OH)2HyLogging VNIR/SWIR / ASD0.35 – 2.5 mHyLogging TIR5.0 – 14.7 mWavenumber [cm-1]Wavelength [m]Vibrational Spectroscopy of Tremolite (Amphibole)nmd = fundamental bending vibrationn = fundamental stretching vibration2,3,4n = 1st, 2nd, 3rd overtone of fundamental stretching vibration52 |Mineral Spectroscopy TheoryFTIR Bruker – Hyperion Microscope100050040020005000370071001000025000

53. 1) Bishop et al. (2008)White Mica Chemistry – mapping exchange vectors Ca-endmember: Margarite (CaAlVI2(AlIV2Si2)O10(OH)2)2200-feature: combination of nOH- (e.g. 3640cm-1) + dAl2OH (e.g. 900cm-1) = 4540cm-1 = 2202nm2350-feature: combination of nOH- + dMg3OH MuscoviteParagoniteCeladoniteFerroceladonitePhengitesFe  MgK  NaFeSi  AlVIAlIVAlVIAlIV  MgSin+dAl2OH: ~2185K  NaNaAlVI2AlIVSi3O10(OH)2KAlVI2AlIVSi3O10(OH)2KFeAlVI2Si4O10(OH)2KMgAlVI2Si4O10(OH)2NaMgAlVI2Si4O10(OH)2NaFeAlVI2Si4O10(OH)2<= Solvus =>2350W2200WK(AlVI,Fe,Mg)1.5AlIV0.5Si3.5O10(OH)2n+dFe3+3OH: ~2355?n+dMg3OH: ~2348n+dAl2OH: ~2190n+dAl2OH: ~221553 |Mineral Spectroscopy Theory

54. Overlapping absorption features Are hydrated phyllosilicates all the same?!? di-octahedral 1:1 phyllosilicate ("7Å phase"): e.g. kaolinitetri-octahedral 2:1 phyllosilicate ("9Å phase"): e.g talcdi-octahedral 2:1 phyllosilicate ("10Å phase"): e.g. muscovite, phengite, celadonitetri-octahedral 2:1 phyllosilicate ("10Å phase"): e.g. biotitetri-octahedral 2:1:1 phyllosilicate ("14Å phase"): e.g. chloriteinterlayeroctahedraltetrahedraltetrahedralall sites occupied?!Meunier (2005)54 |Mineral Spectroscopy Theory

55. Mineral Spectroscopy Theory55 |Geoscience ProDuctapplicable for the listed minerals (examples)Base AlgorithmWhite mica abundance indexPhengite, paragonite/muscovite, illite/brammalite2200D (Relative absorption depth of the 2200 nm absorption for which the continuum is removed between 2120 and 2245, determined using a 3 band polynomial fit around the band with the lowest reflectance) Masked with: 2160D (R2138+R2190)/(R2156 +R2179) < 1.005 and 2350D ((R2326+R2376)/(R2343+R2359)) > 1.005White mica composition indexComposition of white micas, ranging from Al-rich(paragonite/muscovite) to Al-poor (phengite)2200W (Minimum wavelength of the 2200 nm absorption for which the continuum is removed between 2120 and 2245, determined using a 3 band polynomial fit around the band with the lowest reflectance) Masked with: 2160D (R2138+R2190)/(R2156 +R2179) < 1.005 and 2350D ((R2326+R2376)/(R2343+R2359)) > 1.005 Applied stretch based on Duke (1994) Chlorite-epidote(-biotite) abundance indexChlorite, epidote, (biotite)2250D (Relative absorption depth of the 2250 nm absorption for which the continuum is removed between 2230 and 2270, determined using a 3 band polynomial fit around the band with the lowest reflectance) Masked with: 2250D>0.01, 2230 nm<2250wvl<2270 nmChlorite(-biotite) composition indexMg# of chlorite (influenced by epidote and biotite)2250W (Relative absorption depth of the 2250 nm absorption for which the continuum is removed between 2230 and 2270, determined using a 3 band polynomial fit around the band with the lowest reflectance) Masked with: 2250D3pfit>0.01, 2230 nm<2250wvl<2270 nm; 1550D<0.01Applied stretch based on Bishop et al. (2008) Epidote abundance indexEpidote series minerals2250D (Relative absorption depth of the 2250 nm absorption for which the continuum is removed between 2230 and 2270, determined using a 3 band polynomial fit around the band with the lowest reflectance)Masked with: 2250D>0.01, 2230 nm<2250wvl<2270 nm; 1550D>0.01 Epidote composition indexCompositional change of the epidote series minerals, from epidote s.s. to clinozoisite1550W (Relative absorption depth of the 1550 nm absorption for which the continuum is removed between 1500 and 1610, determined using a 3 band polynomial fit around the band with the lowest reflectance)Applied stretch based on Roache et al. (2011) Amphibole talc abundance index3)amphibole group (e.g. actinolite series, hornblende-series), talc group2380D ((R2365+R2415)/(R2381+R2390))Masked with: (R2265+R2349)/(R2316+R2333) > 1.01 +(R2136+R2188)/(R2153+2171) < 1.005) Amphibole composition index3)Mg# of amphibole and talc group2390W (Wavelength of absorption minimum calculated using a fitted 4th order polynomial between 2365 and 2430 nm, focused between 2380 and 2410 nm)Masked with: 2080D<0.01Quartz abundance indexQuartz8635D Relative depth of the 8635 nm Reststrahlen feature for which the continuum is removed between 8565 and 8705 nm, determined using a 3 band polynomial fit around the band with the lowest reflectanceGarnet abundance index (11100P_3pfit)Garnet11100P Relative height of the reflectance peak between 10850 and 11300 nm, determined using a 3 band polynomial fit around the band with the highest reflectanceGarnet composition index (11100W_3pfit)Garnet11100W Wavelength position of the reflectance peak between 10850 and 11300 nm, determined using a 3 band polynomial fit around the band with the highest reflectancePyroxene abundance index (9000P_3pfit)Pyroxene9000P Relative height of the reflectance peak between 8650 and 9350 nm, determined using a 3 band polynomial fit around the band with the highest reflectancePyroxene composition index (9000W_3pfit)Pyroxene9000W Wavelength position of the reflectance peak between 8650 and 9350 nm, determined using a 3 band polynomial fit around the band with the highest reflectanceVesuvianite abundance index (9900P_3pfit)Vesuvianite9900P Relative height of the reflectance peak between 9500 and 10200 nm, determined using a 3 band polynomial fit around the band with the highest reflectanceVesuvianite composition index (9900W_3pfit)Vesuvianite9900W Wavelength position of the reflectance peak between 9500 and 10200 nm, determined using a 3 band polynomial fit around the band with the highest reflectanceCarbonate abundance index (6500P_3pfit)Pyroxene6500P Relative height of the reflectance peak between 10850 and 11300 nm, determined using a 3 band polynomial fit around the band with the highest reflectanceCarbonate composition index (14000DW_3pfit)Pyroxene14000DW Wavelength position of the reflectance minimum between 13000 and 14000 nm, determined using a 3 band polynomial fit around the band with the lowest reflectance