• journal_title：The Canadian Mineralogist
• Contributor：Ştefan Marincea ; Delia-Georgeta Dumitraş ; Cristina Ghineţ ; André-Mathieu Fransolet ; Frédéric Hatert ; Mélanie Rondeaux
• Publisher：Mineralogical Association of Canada
• Date：2011-
• Format：text/html
• Language：en
• Identifier：10.3749/canmin.49.4.1001
• journal_abbrev：Can Mineral
• issn：0008-4476
• volume：49
• issue：4
• firstpage：1001
• section：Articles

Gehlenite is a common mineral in three high-temperature calcic skarns in Romania: Măgureaua Vaţei and Cornet Hill in Apuseni Mountains and Oraviţa in Banat. In all three occurrences, a gehlenite zone occurs within the contact between dioritic or monzodioritic bodies of Upper Cretaceous age and carbonaceous sequences of Mesozoic age. The melilite solid-solutions vary from Ak_34.1 to Ak_51.2 (mean Ak_41.2) at Oraviţa, from Ak_30.4 to Ak_42.9 (mean Ak_38.3) at Măgureaua Vaţei, and from Ak_24.3 to Ak_41.7 (mean Ak_32.9) at Cornet Hill, respectively. The content of “Na-melilite” is low, from up to 1.96 mol.% at Cornet Hill to up to 3.60 mol.% at Oraviţa. The cell parameter a ranges from 7.679(3) to 7.734(3) Å at Oraviţa, from 7.683(4) to 7.735(1) Å at Măgureaua Vaţei, and from 7.684(3) to 7.733(1) Å at Cornet Hill, whereas c varies from 5.043(3) to 5.065(3) Å at Oraviţa, from 5.040(1) to 5.070(3) Å at Măgureaua Vaţei, and from 5.044(1) to 5.067(4) Å at Cornet Hill. It is not possible to quantify the variations in the crystallographic parameters by considering only the åkermanitic substitution because the “Na-melilite” and “Fe-åkermanite” substitutions also play an important role. The cell parameter a remains practically constant within experimental errors, in spite of the increasing åkermanite-for-gehlenite substitution, due to the opposite influence of the “Na-melilite” component. The åkermanite substitution prevails over the opposite influence of “Na-melilite” in increasing the cell volume, and is additive to the influence of “Na-melilite” in decreasing the cell parameter c. The record in the infrared-absorption spectra of bands located at ~855 cm⁻¹ and ~670 cm⁻¹, respectively, which may be tentatively assigned to Al–O–Al stretching, is indicative of the presence of gehlenite-rich members of the melilite group in all the three occurrences.