Optimal slags are the ones located in the olivine domain (fayalite
family, 2FeO.SiO2), since the melting point temperature of the olivines are the lowest of the diagram (eutectic valley around 1100o.C), and these compounds are particularly fluid.
The used standards for major, minor, and REE components were wollastonite (Si), anorthite (Al, Ca), omphacite (Na), olivine (Mg), K-feldspar (K), Zr-jarosite (Zr), ilmenite (Ti), Cr pure (Cr), rhodonite (Mn, Zn), fayalite
(Fe), celestine (Sr), sanbornite (Ba), and F-apatite (F).
 Burnley, P.C., Elastic Plastic Self-Consistent (EPSC) Modeling of Plastic Deformation in Fayalite
Olivine, American Mineralogist, 100, 2015, pp.
Other additives, such as iron oxide and fluxing ESAs, may promote the formation of fayalite
([Fe.sub.2]Si[O.sub.4]) and increase chemical penetration.
Their mineralogical association is characterized by the presence, in order of abundance, of Na-sanidine, greenish iron-rich ferrohedenbergite and fayalite
. Plagioclase and hydrous minerals such as biotite or amphibole are never present in these lavas.
The standards selected for Fe were fayalite
([Fe.sub.2]Si[O.sub.4]), magnetite ([Fe.sub.3][O.sub.4]), goethite (FeOOH), siderite (FeC[O.sub.3]), vivianite ([Fe.sub.3](P[O.sub.4]).8[H.sub.2]O), hematite ([Fe.sub.2][O.sub.3]), green rust-Cl ([(Fe, [Mg.sup.2+]).sub.6] [([Fe.sup.3+]).sub.2][(OH).sub.18].4[([H.sub.2]O).sub.18]Cl), and green rust-S[O.sub.4] ([(Fe,[Mg.sup.2+]).sub.6] [([Fe.sup.3+]).sub.2][(OH).sub.18].4[([H.sub.2]O).sub.18]S[O.sub.4]).
Magnetite is abundant (up to 10%), much of it replacing what may have been fayalite
crystals, by comparison with similar alteration in syenite in the West Barneys River plutonic suite of the Antigonish Highlands in which elict fayalite
has survived (Escarraga 2010).
Typical high temperature non magnetic minerals found in pyrometamorphic rocks associated with coal combustion appear to include several Fe and Al rich clinopyroxene, melilita, cristobalite, tridymite, mullite, cordierite and fayalite
solid solutions, as well as glass (Foit et al., 1987; Cosca et al., 1989; Radan & Radan, 1998).
and Lindsley, D.H.: 1998, Equilibria among titanite, hedenbergite, fayalite
, quartz, ilmenite and magnetite: experiments and internally consistent thermodynamic data for titanite, Amer.
On a more detailed basis, Vert viride (the bluish green used in Station I for the toga worn by Pontius Pilatus) contains chromium oxide (Cr2O3 x 2H2O, Guignet's formula patented in Paris in 1859) plus cobalt oxide giving the bluish shade; Vert olive passe, although containing some chromium oxide, may also have a component of olivine, a rare mineral of volcanic origin including, in variable percentages, green fayalite
and colourless forsterite, two high-fusing point silicates (forsterite 1850[degrees]C; fayalite
1200[degrees]C), a circumstance that would explain the difficulty in producing an enamel with this hue to be processed at temperatures below 1000[degrees]C as, according to the Lenci records, this could not be procured from any of its other suppliers.
The garnet was analyzed for Si, Al, Ti, Fe, Mn, Mg and Ca using the following standards: Si, Mg (pyrope); Al, Mn (spessartine); Ti (titanite); Fe (fayalite
); Ca (diopside); V, Cr, Zn, P, Na, V, Cr, Sr, Y, Zr and Sn were sought but not detected.