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January-February 2018

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Letters

MINERALS OF PALABORA

Shortly after our recent article “The Minerals of Palabora, Limpopo Province, South Africa” went to press in the September/October 2017 issue, a study of the occurrence of rare-earth elements (REEs) in the Palabora carbonatite was published by Giebel et al. (2017). This paper identifies a number of mineral species from the locality that were not included in our list.

All of the additional species have been identified in samples from drill core, in polished thin sections that were examined optically and by electron microscopy. There is no indication that any of the newly listed minerals occur in crystals that would be of interest to most collectors; indeed, they occur as accessory minerals disseminated in the carbonatite matrix. Nevertheless, in the interests of completeness, we provide below a list of the additional minerals that must now be included as reported from Palabora. Note that phases not currently afforded species status by the CNMNC are italicized, and their compositions are as provided by Giebel et al. (2017).

  • Ancylite-(Ce), (Sr,Ca)(Ce,REE)(CO3)2(OH)H2O

  • Anzaite-(Ce), Ce4FeTi6O18(OH)2

  • Barytocalcite, BaCa(CO3)2

  • Bastnäsite-(Ce), (Ce,La)(CO3)F

  • Burbankite, (Na,Ca,)3(Sr,Ba,Ca,REE)3(CO2)3

  • Carbocernaite, (Ca,Na)(Sr,REE)(CO3)2

  • Cordylite-(Ce), NaBaCe2(CO3)4F

  • Fergusonite-(Nd)-β, (Nd,Ce)NbO4

  • Fluorbritholite-(Ce), (Ce,Ca)5(SiO4)3F

  • Parisite-(Ce), Ca(Ce,La)2(CO3)3F

  • “REE-Ti-Betafite-(Ce),” (REE,Ca)2Ti2O6(O,OH,F)

  • “Serpentine Group,” Mg6Si4O10(OH)8

  • Spinel, MgAl2O4

  • Synchisite-(Ce), Ca(Ce,La)(CO3)2F

  • Thorite, (Th,U)SiO4

This extends the list of mineral species (and groups) recorded from Palabora to approximately 115.

PENNSYLVANIA QUARTZ

Subsequent to the publication of my article, “The Smoky Mountain Crystal Prospect, Schuylkill County, Pennsylvania,” in the July/August 2017 issue (pages 366–371), I was fortunate in being able to add another example to my collection (see photo). This wonderful light smoky scepter measures 7.5 cm from base to tip.

The 7.5-cm smoky quartz scepter from Schuylkill County, Pennsylvania.

The 7.5-cm smoky quartz scepter from Schuylkill County, Pennsylvania. John S. White photo.

Rocks & Minerals welcomes letters from our readers. Write rocksandminerals@fuse.net.

REFERENCES

Giebel, R. J., C. D. K. Gauert, M. A. W. Marks, G. Costin, and G. Markl. 2017. Multi-stage formation of REE minerals in the Palabora Carbonatite Complex, South Africa. American Mineralogist 102:1218–33.

Southwood, M. J., and B. Cairncross. 2017. The minerals of Palabora, Limpopo Province, South Africa. Rocks & Minerals 92:426–52.

 

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