Publication details
Minerály skupiny cordieritu v pegmatitech Borského masivu
| Title in English | Cordierite-group minerals from pegmatites of the Bory massif |
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| Authors | |
| Year of publication | 2018 |
| Type | Conference abstract |
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| Citation | |
| Description | This thesis is focused on paragenetic position and chemical composition of cordierite-group minerals (CGM; cordierite, sekaninaite) from granitic pegmatites of the Bory granulite massif. Diferenciated, symmetrically zoned dykes, up to 30 m thick and 0,5 km long were examined. CGM are present in all textural-paragenetic units (from margin to the centre: granitic, graphic, blocky, albite) in these pegmatite dykes. CGM are commonly associated with the assemblage ilmenite + monazite + xenotime. Low resistance of CGM to alterations is the main problem and only small part of samples was suitable for EMP and LA-ICP-MS study. Homovalent substitution Fe-Mg is dominant and Fe is higher in more fractionated CGM. Substitution Fe-Mn (Mg-Mn) is insignificant even in the most fractionated Fe-rich CGM; pegmatite dykes are Mn-poor. Negative correlation of Na versus ?Fe+Mg+Mn suggest heterovalent substitution Na+ + Li+ = ? + R2+, where Li+ enters octahedral position instead of Fe2+, Mg2+ or Mn2+ and charge is stabilized by entrance of Na+ into the channel position. CGM in pegmatites from the Bory granulite massif typically have high contents of Fe and Li (?2243 ppm), but low Mn and Be (?50 ppm) |