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TEMPLATE DESIGN © 2008 www.PosterPresentations.com Abstract–Investigation Purpose Polarized Light Microscopy Differentiation of Erionite from Other “Fibrous” Zeolites Lou Solebello 1 , Gary Tomaino 2 1- International Asbestos Testing Laboratories Inc., Mount Laurel, NJ, 08054 856 231 9449 [email protected] 2-Minerals Technologies Inc, Easton, PA, 18042 610 861-3400, [email protected] X-Ray Diffraction Validation Analysis Spectra Durkee Oregon Type Locality Specimen TEM EDX Example Spectra The purpose of this study was a preliminary assessment of the Polarized Light Microscopy (PLM) central stop dispersion staining technique to differentiate erionite from other “fibrous” (perhaps more appropriately described as elongate mineral particles) zeolites. Erionite is a naturally occurring fibrous mineral belonging to the zeolite group of framework aluminosilicates. Erionite and other zeolites are found in hydrothermally altered volcanic ash deposits and soils formed from erosion of volcanics. The type locality from which erionite was first discovered in Durkee Oregon. Erionite was once considered to be a rare zeolite, but since its first discovery, it has been found elsewhere in the US (North Dakota, Arizona, Nevada, Utah), Australia, Canada, Ireland, Russia, France and the Central Anatolian Region of Turkey. Documented cases of erionite induced mesothelioma in Turkey has resulted in IARC classification of erionite as a Group 1 Carcinogen. Although not currently used in commercial products (formerly used as cracking catalyst), potential health exposure risks to residential and worker populations can occur during open pit mining and soil disturbance during engineering activities. There are at least 80 types of natural and synthetic zeolites, of which less than a dozen natural species occur in a fibrous habit. They possess similar optical, structural and chemical properties which can complicate identification by microscopy techniques. Specimens of erionite, and other fibrous zeolites were procured for structural validation by X-Ray Diffraction Analysis (XRD). PLM was performed on the specimens using a 1.48 “high dispersion” (HD) refractive index liquid (RIL) The 1.48 HD RIL was formulated using appropriate volumes of 1.550 Series E HD RIL and triacetin. The RI of the liquid was calibrated using standardized RI glass beads. PLM analysis was used in conjunction with Central Stop Dispersion Staining (CSDS) to determine if erionite could be differentiated from other fibrous zeolites by CSDS. An approximated 1.47 HD RIL was also formulated for a preliminary examination of a specimen of woolly erionite from the Durkee Oregon type locality. Refractive index of the liquid was estimated by CSDS color of a 1.48 reference glass bead. More precise calibration of the 1.47 RIL to be performed in future. Major cation determination was also performed on specimens using Transmission Electron Microscopy (TEM) Energy Dispersive X-Ray (EDX). Rigaku-DMAX 2200 Ultima Theta-Theta Difractometer 1. Zero background substrate. 2. Tube Voltage-50kV Current-40mA Cu anode 3. Graphite Monochromator 4. Scintillation Counter Detector 5. 0.6mm Receiving Slit, 1 Degree Divergent Slit, 10mm Divergent H.L. 6. 0.02 degree 2-theta steps, 10 second count time per step from 3 degrees two theta to 85 degrees two theta with 30 rpm sample rotation speed. Erionite 1 Erionite (Ehr-ee-on-ite) (K 2 ,Na 2 ,Ca,Mg) 2.1 [Al 4.2 Si 13.8 O 36 ].15H 2 O Named in 1898, by Arthur S. Eakle, from Greek word epiov (wool) for its woolly appearance. Type Locality: Durkee Opal Mine, Swayze Creek, near Durkee, Baker County, Oregon, U.S.A Nomenclature: Potassium-, magnesium-, and calcium-dominant varieties of erionite exist. Morphology Optical Properties Refractive Indices: Omega = 1.455-1.483 , Epsilon = 1.457-1.485 uniaxial positive, positive elongation Often intergrown with offretite, epitaxial overgrowths. Erionite frequently forms very simple hexagonal prisms. Rarely, erionite forms soft, curly, wool-like masses with an asbestiform morphology. Often difficult to distinguish from offretite. ERIONITE OFFRETITE K + Na > Ca + Mg K + Na < Ca + Mg Si/Al = 2.85 to 3.60 Si/Al = 1.99 to 2.80 Uniaxial positive,length slow Uniaxial negative, length fast positive elongation negative sign of elongation RI below 1.485 RI above 1.485 complex XRD pattern Simple XRD pattern 1- Zeolites of the World, Rudy W. Tschernich, Geoscience Press. Inc. 1992 Criteria Frequently Used to Differentiate Erionite From Offretite 1 Specimen PLM/CSDS: Example Images 1.48 “HD” RIL formulated by diluting1.550 Series E RIL (ethyl cinnamate-triacetin) with triacetin and observing with CSDS until a “match” between fluid and 1.48 Cargille reference glass bead was obtained. 1.47 “HD” RIL formulated in same manner, RI of 1.47 estimated on basis of comparison of CSDS of 1.48 glass bead to a CSDS color chart for comparison. Calibration of 1.47 RIL to be performed on future studies. Al: Si = 1:2.2 K:Ca = 5:1 Exp: Si: 48.54, Al: 20.20, K: 11.39, Ca: 1.10 Theo: 47.63 20.21 10.70 Al:Si = 1:2:7 K:Ca = 3:1 Exp: Si: 67.41, Al: 15.18, K: 13.45, Ca: 2.64, Na: 0, Mg: 0 Theo: 56.88, 13.87, 5.28 1.88, 2.42 0.08 chabazite K: 42.50, 22.07, 9.21 1.02 4.73, 0.08 Al:Si = 1:4 K:ca = 1:1 Exp: Si:69.37, Al: 16.30, K: 4.13, Ca: 2.64, Na: 0, Mg: 0 Theo: 67.36, 12.83, 0.54, 3.21, 3.90, 0 Hitachi H-600AB equipped with Evex 7500 detector, Beryllium window, Si crystal Analyses performed at 20,000x magnification, 100KeV accelerating voltage EDS patterns obtained for major cation content Falklands “erionite”, XRD=offretite Beech Creek “erionite” XRD=thomsonite & chabazite Lane Cty natrolite, XRD=natrolite Washington mesolite, XRD=mesolite Oregon mordenite, XRD=mordenite Chase Creek “erionite”, XPL 100X, change in birefringence along fiber length suggest compostional variation Chase Creek “erionite”, 1.48 CSD 100X. Difference in CSS Color suggests compositional variation along fibers Rome Oregon erionite, 100X, 1.48 CSDS. Blue color indicated RI <1.48 Rome Oregon erionite, 200X, 1.48 CSDS, blue CSDS colors indicate RI < 1.48 Inconsistent for erionite Consistent for perlialite Fair agreement…cationic substitution? XRD Identification=offretite XRD Identification=offretite XRD identification=erionite XRD identification=erionite
