Stephen Aja
Professor
Earth and Environmental Sciences
Location: 4223 Ingersoll Hall
Phone: 718.951.5416
Fax: 718.951.4753
Email:
Stephen Aja's Web site
B.Sc.(Hons)Geology; M.Sc. Industrial Mineralogy; PhD, Geology.
Education:
Ph.D., Washington State University - 1989 (Geology)
Areas of Expertise:
Our research activities deal with various aspects of the thermodynamics of clay mineral-water interactions. Clay minerals are major component of minerals near the earth's surface. Clay mineral studies are applicable to petroleum reservoir quality, carbon sequestration in geologic formations, and formation of some ore minerals. Also, the discovery of clay minerals on the surface of Mars intersects with our research interests.
Books and Publications
Aja, S. U. (2021) Resolving the conundrum of equilibrium solubility of smectites. American Mineralogist, In Press. DOI: https://doi.org/10.2138/am-2022-8213 (Books and Publications: Article (Peer-reviewed)) 2021
Aja, S.U.On the thermodynamic stability of illite and I-S minerals. Clays Clay Miner. (2020). https://doi.org/10.1007/s42860-019-00044-x
https://rdcu.be/b1I4q
(Books and Publications: Article (Peer-reviewed)) 2020
Aja, S. (2019) Excess functions of chlorite solid solutions and neoformation of Fe-chlorites: Some implications of recent thermochemical measurements. American Mineralogist, 104, 232 - 243
http://www.minsocam.org/MSA/AmMin/Public_Access/2019_public/AM104P0232.pdf
(Books and Publications: Article (Peer-reviewed)) 2019
Aja, S. U. and Cranganu, C. Exploring the Earth System, 2nd edition, Kendall-Hunt Publishing Co, Dubuque, IA. (Books and Publications: Book (Authored)) 2017
Aja, S. Omotoso, O., Bertoldi, C., Dachs, E. and Benisek, A. (2015) The structure and thermochemistry of three Fe-Mg chlorites. Clays and Clay Minerals, 63, 351-367. (Books and Publications: Article (Peer-reviewed)) 2015
Aja, S.U. and C. Crânganu. Exploring the Earth System. Dubuque, Iowa: Kendall-Hunt. (Books and Publications: Book (Authored)) 2013
Aja, S.U (2002) The stability of Fe-Mg chlorites in hydrothermal solutions: II. Thermodynamic properties. Clays and Clay Minerals, Vol. 50, No. 5, 591-600. (Books and Publications: Article (Peer-reviewed)) 2002
Aja, S.U and Dyar, M. D. (2002) The stability of Fe-Mg chlorites in hydrothermal solutions - I. Results of experimental investigations. Applied Geochemistry, 17, 1219-1239. (Books and Publications: Article (Peer-reviewed)) 2002
Kulik, D.A., Aja, S.U., Sinitsyn, V.A. and Wood, S.A. (2000) Acid-base surface chemistry and sorption of lanthanides on K+-saturated Marblehead illite: II. A multisite surface complexation modeling. Geochimica et Cosmochim Acta, Vol. 64, No. 2, pp. 195-213. (Books and Publications: Article (Peer-reviewed)) 2000
Sinitsyn, V.A., Aja, S.U., Kulik, D.A. and Wood, S.A. (2000) Acid-base surface chemistry and sorption of lanthanides on K+-saturated Marblehead illite: I. Results of an experimental investigation. Geochimica et Cosmichimica Acta, vol. 64, no. 2, pp. 184-195 (Books and Publications: Article (Peer-reviewed)) 2000
Aja, S. U . and Small, J.S. (1999) The solubility of a low-Fe clinochlore between 25 and 175 °C and Pv = PH2O. Eur. J. Mineral., 11, 829-842 (Books and Publications: Article (Peer-reviewed)) 1999
Aja, S.U. (1998) The sorption of the rare earth element, Nd, onto kaolinite at 25 °C. Clays and Clay Minerals, vol. 46, No. 1, 103-109 (Books and Publications: Article (Peer-reviewed)) 1998
Aja, S.U and Kulik, D.A. (1997) An integrated model of equilibrium solubility and sorption of some lanthanides by clay minerals: Application of Gibbs Energy Minimization Techniques. Program Report Prepared for Radioactive Waste Management Program Office of Central Europe and Eurasia, National Research Council/National Academy of Sciences. 138 pp. (Books and Publications: Article (Other)) 1997
Aja, S.U. (1997) An experimental investigation of the sorption of some lanthanides on Marblehead illite in aqueous KCl solutions at 25 °C. Report of Research Investigation prepared for Radioactive Waste Management Program Office of Central Europe and Eurasia, National Research Council/National Academy of Sciences. 36 pp. (Books and Publications: Article (Other)) 1997
Aja, S. U, (1995) Controls on illitization reactions: A thermodynamic approach In M.N. Oti, G. Postma (eds.) Geology of Deltas, A. A. Balkema Publishers, pp. 209 - 216. (Books and Publications: Book Chapter) 1995
Aja, S.U, Wood, S.A. and Williams-Jones, A.E. (1995) The aqueous geochemistry of Zr and the solubility of some Zr-bearing minerals. Applied Geochemistry, vol. 10, pp. 603-620 (Books and Publications: Article (Peer-reviewed)) 1995
Aja, S.U. (1995) Thermodynamic properties of some 2:1 layer clay minerals from solution-equilibration data. Eur. J. Mineral., 7, 325-333. (Books and Publications: Article (Peer-reviewed)) 1995
Aja, S.U and Rosenberg, P.E. (1992) The thermodynamic status of compositionally-variable clay minerals: A discussion. Clays and Clay Minerals, Vol. 40, No. 3, 292-299 (Books and Publications: Article (Peer-reviewed)) 1992
Aja, S.U., Wood, S.A. and Williams-Jones, A.E. (1992) On estimating the thermodynamic properties of silicate minerals. Eur. J. Mineral., 4, 1251-1263. (Books and Publications: Article (Peer-reviewed)) 1992
Aja, S.U, Rosenberg, P.E. and Kittrick, J.A. (1991) Illite equilibria in solutions: II. Phase relationships in the system K2O-Al2O3-MgO-SiO2-H2O. Geochimica et Cosmochimica Acta, Vol. 55, pp. 1365-1374. (Books and Publications: Article (Peer-reviewed)) 1991
Aja, S.U., Rosenberg, P.E and Kittrick, J.A. (1991) Illite equilibria in solutions: I. Phase relationships in the system K2O-Al2O3-SiO2-H2O between 25 and 250 °C. Geochimica et Cosmochimica Acta, Vol. 55, pp. 1353-1364. (Books and Publications: Article (Peer-reviewed)) 1991
Rosenberg, P.E., Kittrick, J.A. and Aja, S.U. (1990) Mixed-layer illite/smectite: A multiphase model. American Mineralogist, Vol. 75, pages 1182-1185. (Books and Publications: Article (Peer-reviewed)) 1990
Conferences, Seminars and Symposiums
The thermodynamic stability of clay minerals: A retrospective In Program & Abstracts, 55th Annual Meeting of the Clay Minerals Society. University of Illinois, Urbana-Champaign, June 11-14, 2018. (Conferences, Seminars and Symposiums: Invited Talk) 2018
Chlorite thermochemistry: Insights from combining calorimetric and solution equilibration data. 53rd Annual Meeting of the Clay Minerals Society, June 5-8, 2016. Atlanta, Georgia. (Conferences, Seminars and Symposiums: Conference Presentation) 2016
"A ternary solid solution model of natural chlorites". 2015 Geological Society of America Annual Meeting. Baltimore, MD. November 4. (Conferences, Seminars and Symposiums: Conference Presentation) 2015
Kulik, D. A. and Aja, S. U. (1997) The hydrothermal stability of illite: Implications of empirical correlations and Gibbs energy minimization. Proceedings of the Fifth International Symposium on Hydrothermal reactions. Gatlinburg, Tennessee. July 20-24, 1997. (Conferences, Seminars and Symposiums: Contributed Talk) 1997
Aja, S.U., Wood, S.A. and Williams-Jones, A.E. (1993) Synthesis and solubility of neodymium hydroxybastnaesite In Proceedings of the 4th International Symposium on hydrothermal reactions, eds. M. Cuney and M. Cathelineau, pp. 3-6, Vandoeuvre-les-Nancy, France. (Conferences, Seminars and Symposiums: Conference Presentation) 1993