Mineral Sciences Staff
- Jeffrey E. Post
- Geologist - Curator-in-Charge, Mineral Collection
- Phone: (202) 633-1814
- Fax: (202) 357-2476
- E-mail Address: postj
- Mailing Address:
PO Box 37012, MRC 119
Washington, DC 20013-7012
- Shipping Address:
National Museum of Natural History
10th & Constitution NW
Washington, DC 20560-0119
Ph.D. Arizona State University (1981)
For the past several years I have coordinated a research effort into the study of mineral structures and behaviors, with a focus on environmentally significant minerals. Mineral groups such as clays, manganese oxides and iron oxides tend to accumulate in soils and sediments and on rock surfaces where they interact directly with the atmosphere, hydrosphere, and biosphere. Many of these minerals are chemically active, readily participating in oxidation-reduction reactions, serving as cation-exchange agents, and absorbing a variety of heavy metal cations, and many form as a result of biological mediation. They typically are fine-grained, and consequently even small quantities exhibit large surface areas and can significantly affect the chemistry of the local environment. Many of the phases and their synthetic analogues are also subjects of intense research as possible catalysts, battery materials and chemical sieves for a variety of industrial and pollution abatement applications. Their fine-grained nature has made it difficult to study the structures and behaviors of these minerals using traditional laboratory methods. We have taken advantage of recent advances in powder and single-crystal X-ray and neutron diffraction, as well as a variety of spectroscopic and sophisticated computer modeling procedures to attempt to provide a first order understanding of the structure and chemical properties of many of these phases.
Recent research activities
During the past three years, we have bee successful with two proposals for beam time at the National Synchrotron Light Source, Brookhaven National Laboratory. The very specialized instrumentation permits real-time X-ray diffraction studies of dehydration and cation-exchange reactions for manganese oxides and clay minerals. One result of our studies has been the discovery of a manganese oxide mineral having a new structure type with huge tunnels; it is being investigated as a prototype for a new class of catalysts and molecular sieves.
During the past year David Mckeown and I completed our study of manganese oxide dendrites and manganese-rich desert varnishes that coat many of the rock surfaces in southwestern United States and other arid regions. Previous attempts to characterize these materials using TEM and X-ray diffraction have been unsuccessful because the samples tend to be very poorly crystalline mixtures. During the past two years we completed two very successful EXAFS experiments at Brookhaven National Laboratory, resulting in data for approximately 50 samples, including dendrites, desert varnish, and standards. The paper describing this work was published earlier this year in "American Mineralogist". I was also asked to give an invited talk on this work at this year's Goldschmidt Conference.
Post, J.E., Von Dreele, R.B., and Buseck, P.R. (1982) Symmetry and cation displacements in hollandites: structure refinements of hollandite, cryptomelane, and priderite. Acta Crystallographica, B38, 1056-1065.
Fegley, B., and Post, J.E. (1983) Mineral Chemistry of a large spinel-rich inclusion in the Kaba CV3 chondrite. Lunar and Planetary Sciences, 15, 264-265.
Post, J.E., and Buseck, P.R. (1983) Characterization of individual particles in the Phoenix urban aerosol, using electron beam instruments. Environmental Science and Technology, 18, 35-42.
Post, J.E., and Buseck, P.R. (1983) Energy-dispersive X-ray analysis of individual particles from two secondary iron foundries. Microbeam Analysis, 182-186.
Veblen, D.R., and Post, J.E. (1983) A TEM study of fibrous cuprite (chalcotrichite): microstructures and growth mechanisms. American Mineralogist, 68, 790-803.
Fegley, B., and Post, J.E. (1985) A refractory inclusion in the Kaba CV3 chondrite: some implications for the origin of spinel-rich chondrules and inclusions in chondrites. Earth and Planetary Science Letters, 75, 297-310.
Chamberlain, C.P., Docka, J.A., Post, J.E., and Burnham, C.W. (1985) Scapolite: alkali atom configurations, antiphase domains, and compositional variations. American Mineralogist, 70, 134-140.
Marvin, U.B., and Post, J.E. (1985) Searching for evidence of an impact event at the Cretaceous/Tertiary boundary on Seymour Island. Antarctic Journal of the U.S., 14, 42-43.
Post, J.E., and Buseck, P.R. (1985) Quantitative energy-dispersive analysis of lead halide particles from the Phoenix urban aerosol. Environmental Science and Technology, 19, 682-685.
Post, J.E., and Burnham, C.W. (1986) Modeling Tunnel-cation displacements in hollandites using structure-energy calculations. American Mineralogist, 71, 1178-1185.
Post, J.E., and Burnham, C.W. (1986) Ionic modeling of structures and energies in the electron-gas approximation: TiO2 polymorphs, quartz, forsterite, diopside. American Mineralogist, 71, 142-150.
Docka, J.A., Post, J.E., Bish, D.L., and Burnham, C.W. (1987) Positional disorder of the A-site cations in C2/m amphiboles: model energy calculations and probability studies. American Mineralogist, 72, 949-958.
Post, J.E., and Burnham, C.W. (1987) Structure-energy calculations on low and high albite. American Mineralogist, 72, 507-514.
Post, J.E., and Appleman, D.E. (1988) Chalcophanite, ZnMn3O73H2O: New crystal-structure determinations. American Mineralogist, 73, 1401-1404.
Post, J.E., and Bish, D.L. (1988) Rietveld refinement of the todorokite structure. American Mineralogist, 73, 861-869.
Turner, S., and Post, J.E. (1988) Refinement of the substructure and superstructure of romanechite. American Mineralogist, 73, 1155-1161.
Abbott, R.N., Jr., Post, J.E., and Burnham, C.W. (1989) Treatment of the hydroxyl in structure-energy calculations. American Mineralogist, 74, 141-150.
Bish, D.L., and Post, J.E. (1989) Thermal behavior of complex, tunnel-structure manganese oxides. American Mineralogist, 74, 177-186.
Morris, D.E., Asmar, N.G., Nickel, J.H., Sid, R.L., Wei, J.Y.T., and Post, J.E. (1989) Stability of 124, 123, and 247 superconductors. Physica C, 159, 287-294.
Morris, D.E., Asmar, N.G., Wei, J.Y.T., Nickel, J.H., Sid, R.L., Scott, J.S., and Post, J.E. (1989) Synthesis and properties of the 2:4:7 superconductors R2Ba4Cu7O15-x (R=Y,Eu,Gd,Dy,Ho,Er). Physical Review B, 40, 11406-11409.
Morris, D.E., Nickel, J.H., Wei, J.Y.T., Asmar, N.G., Scott, J.S., Scheven, U.M., Hultgren, C.T., Markelz, A.G., Post, J.E., Heaney, P.J., Veblen, D.R., and Hazen, R.M. (1989) Eight new high-temperature superconductors with the 1:2:4 structure. Physical Review B, 39, 7347-7350.
Post, J.E., and Bish, D.L. (1989) Rietveld refinement of the coronadite structure. American Mineralogist, 74, 913-917.
Post, J.E., and Bish, D.L. (1989) Rietveld refinements of crystal structures using powder X-ray diffraction data. In "Modern Powder Diffraction", Bish, D.L., and Post, J.E., Editors, 277-308.
Abbott, R.N.,Jr., Burnham, C.W., and Post, J.E. (1990) Hydrogen in humite-group minerals: structure-energy calculations. American Mineralogist, 74, 1300-1306.
Post, J.E., and Veblen, D.R. (1990) Crystal structure determinations of three synthetic birnessites using TEM and the Rietveld method. American Mineralogist, 75, 477-489.
Post, J.E. and Buchwald, V.F. (1991) Crystal structure refinement of akagan‚ite. American Mineralogist. 76, 272-277.
Heaney, P.J. and Post, J.E. (1992) The widespread distribution of a novel silica polymorph in microcrystalline quartz varieties. Science. 255, 441-443.
Heaney, P.J., Post, J.E. and Evans, H. (1992) The crystal structure of bannisterite. Clays and Clay Minerals, 40, 129-144.
Post, J.E. (1992) Crystal structures of manganese oxide minerals. In Biomineralization, processes of iron and manganese, Ed. H.C.W. Skinner and R.W. Fitzpatrick, Catena Supplement 21, Catena Verlag, Germany
Reid, P.R., Macintyre, I.G., and Post, J.E. (1992) Micritized skeletal grains in northern Belize lagoon: a major source of Mg-calcite mud. Journal of Sedimentary Petrology, 62, 145-156.
Bish, D.L. and Post, J.E. (1993) Quantitative mineralogical analysis using the Rietveld full-pattern fitting method. American Mineralogist, 78, 932-940.
Evans, H.T., Post, J.E., Ross, D.R., and Nelen, J.A. (1994) The crystal structure and crystal chemistry of fernandinite and corvusite. Canadian Mineralogist, 32, 339-351.
Heaney, P.J., Veblen, D.R., and Post, J.E. (1994) Structural disparities between chalcedony and macrocrystalline quartz. American Mineralogist. 79, 452-460.
Post, J.E. and Appleman, D.E. (1994) Crystal structure refinement of lithiophorite. American Mineralogist, 79, 370-374.
Dai, Y. , Post, J.E., and Appleman, D.E. (1995) Crystal structure of minehillite: twinning and structural relationships to reyerite. American Mineralogist, 80, 173-178.
Dai, Y. and Post J.E. (1995) Crystal structure of hillebrandite: a natural analogue of calcium silicate hydrate (CSH) phases in Portland cement. American Mineralogist, 80, 841-844.
Mandernack, K.W., Post, J.E., and Tebo, B.M. (1995) Manganese mineral formation by bacterial spores of the marine Bacillus, strain SG-1:evidence for the direct oxidation of Mn(II) to Mn(IV). Geochimica et Cosmochimica Acta 59, 4393-4408.
Post, J.E. (1997) The National Gem Collection. Harry Abrams, Inc., New York, 144p.
Fritsch, S., Post, J.E. and Navrotsky, A. (1997) Energetics of low temperature polymorphs of manganese dioxides and oxyhydroxides. Geochimica et Cosmochimica Acta, 61, 2613-2616.
Fritsch, S., Post, J.E., Suib, S.L. and Navrotsky, A. (1998) Thermochemistry of framework and layer manganese dioxide related phases. Chemistry of Materials, 10, 474-479.
Post, J.E. (1999) Manganese oxide minerals: crystal structures and economic and environmental significance. In Colloquium on Geology, Mineralogy, and Human Welfare, J.V. Smith (ed.), National Academy of Sciences, Washington, DC. 3447-3454.
Ni,Y., Post, J.E. and Hughes, J. M. (2000) The crystal structure of parisite-(Ce), Ce2CaF2(CO)3. American Mineralogist, 85, 251-258.
Heaney, P.J. and Post, J.E. (2001) Evidence for an I2/a to Imab phase transition in the silica polymorph moganite at ~570 K. American Mineralogist, 86, 1358-1366.
McKeown, D.A. and Post, J.E. (2001) Characterization of manganese oxide mineralogy in rock varnish and dendrites using X-ray absorption spectroscopy. American Mineralogist, 86, 701-713.
McKeown, D.A., Post, J.E. and Etz, E.S. (2002) Vibrational Analysis of Palygorskite and Sepiolite, Clays and Clay Minerals, 50, 667-680.
Peslier, A, Luhr, J. and Post, J.E. (2002) Low water contents in pyroxenes from spinel-peridotites of the oxidized, sub-arc mantle wedge. Earth and Planetary Science Letters, 201,69-86.
Post, J.E., Heaney, P.J. and Hanson, J. (2002) Rietveld refinement of a triclinic structure for synthetic Na-birnessite using synchrotron powder diffraction data. Powder Diffraction, 17, 218-221.
Post, J.E., Heaney, P.J., Von Dreele, R.B. and Hanson, J. (2003) Neutron and temperature-resolved synchrotron X-ray powder diffraction study of akaganéite. American Mineralogist, 782-788.
Post, J.E., Heaney, P.J. and Hanson, J. (2003) Real-time synchrotron X-ray powder diffraction studies of the structure and dehydration of todorokite. American Mineralogist, 88, 142-150.
Post, J.E., Heaney, P.J., Cahill, C.L. and Finger, L. (2003) A new Mn oxide structure type with 3x4 tunnels. American Mineralogist, In Press.
Post, J.E. and Heaney, P.J. (2003) Neutron and Synchrotron powder diffraction study of ramsdellite and groutellite. Submitted to American Mineralogist.
Post, J.E. and Heaney, P.J. (2004) Neutron and Synchrotron powder diffraction study of ramsdellite and groutellite. American Mineralogist. 89, 969-975.
Komarneni, S., Newalkar, B.L., Li, D., Gheyi, T., Lopano, C.L., Heaney, P.J., and Post, J.E. (2004) Kinetics of nitrate ion exchange from anionic clays. Journal of Porous Materials. 10, 243-248
Ertl, A., Pertlik, F., Prem, M., Post, J.E., Kim, S.J., Schuster, R., and Brandstatter, F. (2005)Ranciéite crystals from Friesach, Carinthia, Austria. European Journal of Mineralogy. 17, 163-172.
Johnson E.A. and Post, J.E. (2006) Water in the interlayer region of birnessite:importance in cation exchange and structural stability. American Mineralogist, 91, 609-619.
Heaney, P.J., McKeown, D.A., and Post, J.E. (2007) Anomalous behavior at the I2/a to Imab phase transition in SiO2-moganite: An analysis using hard-mode Raman spectroscopy. American Mineralogist 92, 631-639.
Lopano, C.L., Heaney, P.J., Post, J.E., Hanson, J. and Komarneni, S. (2007) Time-resolved structural analysis of K-and Ba-exchange reactions with synthetic Na-birnessite using synchrotron X-ray diffraction. American Mineralogist 92, 380-387.
Post, J.E., Bish, D.L., and Heaney, P.J. (2007) Synchrotron Powder X-ray Diffraction Study of the Structure and Dehydration Behavior of Sepiolite. American Mineralogist, 92, 91-97.
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