Where it forms, where it's found
- Geological setting
metastable phase crystallizing rapidly in a silicate melt enclosed in a small pore under non-equilibrium conditions. This phase is always found entirely enclosed in former silicate melt droplets, now completely crystallized as nanogranitoids in garnet.
- Type locality
- Pfaffenberg hill
- Waldheim
- Mittelsachsen
- Saxony
- Germany
51.0686°, 13.0153°
4recorded occurrences
Crystallography
- Space group
- P6/mcc
- Cell parameters
- a = 10.277(1) Å · c = 14.722(3) Å
- Z
- 2
- Type-locality form
size up to 20 μm and isometric shape, locally reaching negative crystal shape, i.e., mimicking the shape of the host garnet
Chemical composition
Synonyms
- Pfaffenbergiet
- Phase 412
In other languages
- German
- Pfaffenbergit
Classification
Strunz
10th ed.9.FA.75
- 9SilicatesClass
- 9.FTektosilicates without zeolitic H2ODivision
- 9.FATektosilicates without additional non-tetrahedral anionsGroup
- 9.FA.75PfaffenbergiteSpecies
Group, growth & confusion
Literature, links & citation
Citations
- —Ferrero, S., Lorenzon, S., Borriello, R., Mugnaioli, E., Borghini, A., Fuchs, R., Wirth, R., Schreiber, A., and Grew, E. S.: Pfaffenbergite, IMA 2023-105, in: CNMNC Newsletter 78, Eur. J. Mineral., 36, https://doi.org/10.5194/ejm-36-361-2024, 2024.
- 2026Ferrero, Silvio; Lorenzon, Sofia; Borriello, Roberto; Borghini, Alessia; Wirth, Richard; Schreiber, Anja; Fuchs, Rico; O’Brien, Patrick J.; Grew, Edward S.; Mugnaioli, Enrico (2026) Pfaffenbergite, KNa3(Al4Si12)O32, a polymorph of sodic feldspar isostructural with kokchetavite and wodegongjieite, found in crystallized melt inclusions in metamorphic garnet. American Mineralogist, 111 (1). 60-72 doi:10.2138/am-2025-9750DOI: 10.2138/am-2025-9750
Cite this entry
@misc{mineral2026,
author = {Mineral Index editorial board},
title = {Pfaffenbergite — Mineral Index},
year = {2026},
url = {https://mineralindex.org/minerals/pfaffenbergite-471051},
note = {Accessed 2026-05-11}
}