New Minerals Reported by European Journal of Mineralogy

The most recent issue (volume 38) of the European Journal of Mineralogy includes three papers that introduce previously unknown mineral species and report novel geological processes.

Thermally Activated Multistep Alteration of Fe²⁺‑Bearing Fluorophlogopite Christian Reinberg, Stylianos Aspiotis, Thomas Malcherek, Stefan T. M. Peters, and Boriana Mihailova used in situ high‑temperature Raman spectroscopy to study fluorophlogopite containing interlayer K⁺ and Fe²⁺. Their work shows a phonon‑driven structural instability near 600 K that mobilizes K⁺ as charge carriers. Above 1100 K H⁺ cations delocalize and contribute to transport, while at temperatures above 1300 K oxidation of Fe occurs together with limited dehydrogenation and dehydroxylation, leading to partial K⁺ leakage and structural decomposition ¹.

Xianhuaite-(Ce), K₂CeNb₅O₁₅ – A New Niobium Mineral from Bayan Obo, China Researchers Bo Yang, Yuan Xue, Li Yang, Ningyue Sun, Guowu Li, Junfang Yu, Guoying Yan, Jianyong Liu, Yonggang Zhao, Wenxiang Meng, Zhenyu Chen, Lei Chen, Ze Liu, Zhao Yan, Xinyu Hou, Xin Ao, and Jinlong Wang reported the discovery of xianhuaite-(Ce) (chemical formula K₂CeNb₅O₁₅) in the Bayan Obo deposit in northern China. The mineral contains potassium, cerium, and niobium; its structure was determined by microscopy, chemical analysis, and X‑ray diffraction. This finding enhances understanding of how rare‑earth and niobium ores form in geological settings ¹.

Fluorine‑Induced Melting in the Ihalainen Calcite‑Wollastonite Marble Deposit, Lappeenranta, Finland Robert F. Martin, Dirk Schumann, Markku J. Lehtinen, and Sebastian Fuchs describe fluorine‑induced melting at the Ihalainen marble deposit near Lappeenranta, Finland. The deposit originally produced wollastonite, a calcium silicate that formed 1.86 × 10⁹ years ago. About 240 × 10⁶ years later, a fluorine‑rich granitic magma intruded the host marble. Loss of silica and alkalis from the silicate magma caused the marble to melt. Fluorine‑rich vapor mobilized niobium, tantalum, and tin, producing previously unknown minerals. Initially CO₂‑dominant fluid became aqueous, forming a complex assemblage of alteration minerals ¹.