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Paper No. 11
Presentation Time: 8:00 AM-6:00 PM

MICROPROBE ANALYSIS OF ERIONITE, KILLDEER MOUNTAINS, NORTH DAKOTA


TRIPLETT, Jason, Environmental and Conservation Sciences, North Dakota State University, Stevens Hall, Fargo, ND 58108, SAINI-EIDUKAT, Bernhardt, Department of Geosciences, North Dakota State Univ, Fargo, ND 58108-6050, FEIT, Sharon, Dept. of Integrative Biology, University of South Florida, 4202 East Fowler Ave, SCA110, Tampa, FL 33620 and DOLEZAL, Dillon, Dept. of Geosciences, North Dakota State University, Stevens Hall, Fargo, ND 58108-6050, bernhardt.saini-eidukat@ndsu.edu

The fibrous zeolite mineral erionite is a concern due to its potential for causing pleural diseases, including malignant mesothelioma (PMM) in humans (Emri et al 2002 Tox Let 127:251). Low-level environmental exposure to erionite-bearing altered volcanic bedrock may be the explanation for a high PMM rate in certain locations. Epidemiologic studies suggest erionite could potentially be more active and toxic than some forms of asbestos (Metintas et al 1999 Eur Resp J 13:523).

The presence of erionite in North Dakota was reported by Forsman (1986 NDGS RI 87) as occurring in the Killdeer Mountains (KDM), one of a number of prominent buttes in western North Dakota. It was discovered in volcanic tuffs of the late Oligocene to early Miocene Arikaree Formation. Other formations throughout western North Dakota, South Dakota, and Montana have been recognized as erionite-bearing (Goodman and Pierson, 2010 GSA Abstr. 42(3):5).

For the study reported here, 23 rock and/or soil samples were taken from the KDM. Samples were prepared by flotation in a water column followed by vacuum filtration to separate any zeolite fibers from larger size fractions. Powder X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were carried out at NDSU. Eight samples were selected for electron microprobe analysis (EMPA) at University of Minnesota. Of those, 28 individual fibers (77 points) were measured.

EMP analyses were evaluated using the guidelines established for erionite identification by Dogan and Dogan (2008 Environ Geochem Health 30:355) and Passaglia et al (1998 Am Min 83:577). Most analyses show Mg (ions/72 oxygen) > 0.8; E > +/- 10%, and Mg/(Ca+Na) > 0.3. These values point toward the majority of KDM fibers not meeting the criteria for identification as erionite. In fact, only 3 analyses met the criteria.

The results of this study are consistent with those of Lowers and Meeker (2007 Denver microbeam lab rep 14012007), who analyzed fibers separated from ND soil and roadbed samples. SEM/EDS data plot in both regions of erionite and offretite.

Acknowledgment: NIH grant P20 RR016471 from INBRE/NCRR.

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