Fluoro-edenite

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Fluoro-edenite
Fluoro-edenite9388-9.jpg
Fluoro-edenite
General
Category Inosilicate minerals, amphibole group
Formula NaCa2Mg5(Si7Al)O22F2
IMA symbol Fed
Strunz classification 9.DE.15
Crystal system Monoclinic
Crystal class 2/m - Prismatic
Space group P2/m (space group 10)
Unit cell a = 9.847 Å, b = 18.017 Å, c = 5.268 Å β = 104.84°
Identification
ColourLight green to light yellow, grey-black
Crystal habit Prismatic, acicular, fibrous (asbestiform)
Twinning None mentioned
Cleavage Perfect on {110}
Tenacity Brittle
Mohs scale hardness5 - 6
Luster Vitreous
Streak Grey-white, yellowish white
Specific gravity 3.09 (Calculated)
Density 3.09 g/cm3 (Calculated)
Optical propertiesBiaxial (-)
Refractive index nα = 1.6058(5) nβ = 1.6170(5) nγ = 1.6245(5)
Birefringence δ = 0.019
Pleochroism Not visible
2V angle Calculated: 78°
Dispersion r < v
ExtinctionY ≡ β ⊥ (010), γ ⊥ Z = 26°.
Ultraviolet fluorescence None
Absorption spectra In the 1300–450 cm–1 range, significant absorption bands occur at 1066, 991, 791, 738, 667, 517, and 475 cm–1.
References [1] [2]

Fluoro-edenite is a rare amphibole mineral that contains sodium, calcium, magnesium, aluminium, silicon, oxygen and fluorine. It belongs to the same family as the more common mineral edenite but has fluorine as a key component. Fluoro-edenite was first discovered in volcanic rocks near the town of Biancavilla on the south-western flank of Mount Etna in Sicily. It has since been reported in smaller amounts in other locations.

Contents

Chemistry

Fluoro-edenite is part of the calcic amphibole group, a subgroup of the amphibole mineral family. Its chemical formula is NaCa2Mg5(Si7Al)O22F2, which means it is made mainly of sodium, calcium and magnesium combined with silica, aluminium and fluorine. [3] Like other amphiboles, its structure is based on double chains of silica tetrahedra, and it crystallises in the monoclinic crystal system. X-ray and infrared studies show that its atomic arrangement is very similar to other fluorine-rich amphiboles in the edenite–pargasite series. [4]

Location

Fluoro-edenite was first discovered is Monte Calvario, close to Biancavilla in eastern Sicily. Here, Fluoro-endnite occurs as prismatic and fibrous crystals in benmoreitic lava that has been altered by hot, fluorine-rich fluids rising through the volcanic rocks of Mount Etna. The same rock has been quarried for sand and aggregate used in local building and road works, which has spread fluoro-edenite fibres into the surrounding environment. [5]

Fluoro-edenite has also been found in Cobden, Ontario, Canada. At that location, it forms dark green to almost black crystals in metamorphic rocks. Samples in this location have been studied using X-ray diffraction together with Raman and infrared spectroscopy to confirm their identity. [6]

Toxicity

Health studies in Biancavilla have found a higher-than-expected number of pleural mesothelioma cases compared with similar populations. The excess has been linked to long-term exposure to airborne fluoro-edenite fibres released from the Monte Calvario quarry. It was proven not to be from any asbestos minerals. [7]

Laboratory experiments using human lung epithelial cells show that fluoro-edenite fibres can attach to the cells, and slow down their growth. The fibres also trigger the release of inflammatory molecules, suggesting a pattern of damage similar to that caused by asbestos fibres and fibrous zeolites. [8]

Based on community studies in Biancavilla and the experimental work on fibres, the International Agency for Research on Cancer has classified fibrous fluoro-edenite as carcinogenic to humans (Group 1), concluding that there is sufficient evidence that exposure can cause mesothelioma. [9]

References

  1. ↑ "Fluoro-edenite". mindat.org. Mindat. 4 December 2025. Retrieved 4 December 2025.
  2. ↑ "Mindat.org". mindat.org. Mindat. 4 December 2025. Retrieved 4 December 2025.
  3. ↑ Gianfagna, Antonio; Oberti, Roberta (2001). "Fluoro-edenite from Biancavilla (Catania, Sicily, Italy): Crystal chemistry of a new amphibole end-member". American Mineralogist. 86: 1489–1493. doi:10.2138/am-2001-11-1217.
  4. ↑ Della Ventura, Giancarlo; Bellatreccia, Fabio; Cámara, Fernando; Oberti, Roberta (2014). "Crystal-chemistry and short-range order of fluoro-edenite and fluoro-pargasite: A combined X-ray diffraction and FTIR spectroscopic approach". Mineralogical Magazine. 78 (2): 293–310. doi:10.1180/minmag.2014.078.2.05.
  5. ↑ "Fluoro-edenite". Some Nanomaterials and Some Fibres. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Vol. 111. Lyon: International Agency for Research on Cancer. 2017. Retrieved 4 December 2025.
  6. ↑ "Fluoro-edenite R070003". RRUFF Project. University of Arizona. Retrieved 4 December 2025.
  7. ↑ Comba, Pietro; Gianfagna, Antonio; Paoletti, Luigi (2003). "Pleural mesothelioma cases in Biancavilla are related to a new fluoro-edenite fibrous amphibole". Archives of Environmental Health. 58 (4): 229–232. doi:10.3200/AEOH.58.4.229-232. PMID   14655903.
  8. ↑ Travaglione, Sara; Bruni, Biagio; Falzano, Loredana; Paoletti, Luigi; Fiorentini, Carla (2003). "Effects of the new-identified amphibole fluoro-edenite in lung epithelial cells". Toxicology in Vitro. 17 (5–6): 547–552. doi:10.1016/S0887-2333(03)00118-8. PMID   14599443.
  9. ↑ Bateson, Thomas F.; Benbrahim-Tallaa, Lamia; Bouvard, Véronique; et al. (2014). "Carcinogenicity of fluoro-edenite, silicon carbide fibres and whiskers, and carbon nanotubes". Lancet Oncology. 15 (13): 1427–1428. doi:10.1016/S1470-2045(14)71109-X. PMID   25499275.
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