merwinite

merwinite

[′mər·wə‚nīt]
(mineralogy)
Ca3MgSi2O8 A rare colorless or pale-green neosilicate mineral crystallizing in the monoclinic system; occurs in granular aggregates showing polysynthetic twinning; hardness is 6 on Mohs scale, and specific gravity is 3.15
References in periodicals archive ?
The analysis showed that the composition of the original ash sample included mainly quartz, lime, anhydrite, calcite and smaller amounts of orthoclase, periclase, gehlenite, larnite, merwinite, pseudowollastonite, hematite, ettringite, melilite and dolomite (Table 2).
In addition, illite (6.5%), gehlenite (6.3%), dolomite (3.0%), larnite (2.3%), hematite (2.3%), periclase (1.3%), wollastonite (1.0%), merwinite (0.9%), ettringite (0.7%), melilite (0.3%) and calcium aluminate hydrate (0.3%) are present.
TEHRAN (FNA)- An Iranian researcher from Material and Energy Research Center in association with scientists from Research and Clinical Center for Infertility of Shahid Sadoughi University of Medical Sciences of Yazd studied repairing damaged bone tissues of rats by using nanostructured bioceramic based on silicate magnesium calcium (merwinite) and compared it to hydroxyapatite commercial powder.
Olivine, merwinite, calcium silicates ([C.sub.2]S, [C.sub.3]S), [C.sub.4]AF, [C.sub.2]F, CaO-FeO-MnO-MgO in solid solution and free CaO are common minerals in steel slag (Shih et al.
In addition, the content of other secondary Ca-silicates (merwinite, wollastonite and akermanite) is remarkably lower (< 12% in total) than in other oil shale ashes [17].
In CFB OSA samples, silica compounds were mainly represented by quartz (Si[O.sub.2]) and orthoclase type K-feldspar (KAlSi[O.sub.3]), while the PF OSA samples contained noticeably more secondary silicates--belite ([Ca.sub.2]Si[O.sub.4]) and merwinite ([Ca.sub.3]Mg[(Si[O.sub.4]).sub.2]).
In both cases, Mg was found to be mostly present as periclase (MgO) and also partially bound as undecomposed carbonates (dolomite--CaMg[(C[O.sub.3]).sub.2] can be found in the CFBC bottom ash) or silicates (merwinite, [Ca.sub.3]Mg[(Si[O.sub.4]).sub.2], melilite, [(Ca,Na).sub.2](Mg,Al)[(Si,Al).sub.3][O.sub.7]).
In the Balti TPP the Ca-silicates are represented by C2S (belite--[beta]-Ca[Si.sub.2][O.sub.4]), merwinite [[Ca.sub.3]Mg[(Si[O.sub.4]).sub.2]] and wollastonite type phases (CaSi[O.sub.3]).
SEM analyses together with EDX element mapping revealed that particles of PF/CA can be divided generally into three types: spherical homogeneously melted ones--they contain Ca-Mg-Al-silicates: melilite [(Ca,Na).sub.2](Mg,Al)[(Si,Al).sub.3][O.sub.7], illite-smectite, merwinite ([Ca.sub.3]Mg[(Si[O.sub.4]).sub.2] (Fig.
In addition to these minerals, fresh semi-coke contains secondary phases formed by partial thermal decomposition and subsequent reactions of carbonate and clay minerals--melilite [[(Ca,Na).sub.2](Al,Mg,Fe)[(Si,Al).sub.2][O.sub.7]], periclase [MgO], clinker-minerals: belite [[beta]-C2S], merwinite [Ca3Mg(SiO4)2].
Mg was found in both cases mainly as periclase (MgO), partially bound to carbonates (dolomite) or silicates (merwinite).
Troilite FeS, brookite Ti[O.sub.2], siderite FeC[O.sub.3], iron sulfate [Fe.sub.2][(SO4).sub.3], aluminium oxide [Al.sub.2][O.sub.3] and many magnesium compounds--clinoenstatite MgSi[O.sub.3], bredigite [Ca.sub.14][Mg.sub.2][(Si[O.sub.4]).sub.8], merwinite [Ca.sub.3]Mg[(Si[O.sub.4]).sub.2], huntite [Mg.sub.3]Ca[(C[O.sub.3]).sub.4], calcite magnesian (Ca,Mg)C[O.sub.3], sodium calcium magnesium silicate [Na.sub.2][Ca.sub.4][Mg.sub.2][Si.sub.4][O.sub.15] are probably also present.