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Iron valence measurements were calibrated using Fe-bearing mineral standards of known Fe valence: fayalite ([Fe.sup.2+.sub.2] Si[O.sub.4]), magnetite, and hematite ([Fe.sup.3+.sub.2][O.sub.3]).
Using the derived value of 7.16 gives high computed [rho]NCS value of 5.00 g/[cm.sup.3] for fayalite glass in comparison with 4.326 of Holland and Powell (1998).
Standards and elements lines were as follows: magnesian manganoan fayalite (SiK[alpha], MgK[alpha], MnK[alpha], and FeK[alpha]), synthetic anorthite (AlK[alpha] and CaK[alpha]), rutile (TiK[alpha]), synthetic ZnO (ZnK[alpha]), Amelia albite (NaK[alpha]), and microcline (KK[alpha]).
Chemical microanalysis has determined that dross commonly found in ductile iron applications contains magnesium oxide (MgO), silica (Si[O.sub.2]), magnesium sulfide (MgS), forsterite ([Mg.sub.2]Si[O.sub.4]), enstatite (MgSi[O.sub.3]), alumina ([Al.sub.2][O.sub.3]), fayalite ([Fe.sub.2]Si[O.sub.4]), silicides and amorphous silicates.
Gross (1962) reported the occurrence of fayalite in an "augite syenite."
Once formed, FeO can react with silica to form iron silicate or fayalite. This is a liquid at metal pouring temperature that easily wets the surface of the silica and runs between the sand grain.
Associated minerals are: zircon, quartz, kainosite-(Y), aegirine, [beta]-fergusonite-(Y), yttrian ilvaite, ilvaite, hingganite-(Ce), neodymian allanite-(Ce), magnetite, fayalite and fluorite.
The role of iron oxide in preventing porosity has long been linked with its ability to react with silica to form fayalite, which forms a "physical" barrier, preventing gas solution.
The following standards were used: diopside (Si, Ca), spessartine (Mn), fayalite (Fe), andalusite (Al) and forsterite (Mg).
Most foundrymen were taught that seacoal acts by burning and producing a reducing atmosphere, which prevents oxidation of the cast iron, and consequently prevents the formation of fayalite and ultimately Penetration.