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About ThermessaiteHide

colourless to white
Specific Gravity:
Crystal System:
Named after Thermessa, an ancient Greek name of the island of Vulcano meaning "the warm island".
Isostructural with:
The K-analogue of thermessaite-(NH4).

This mineral contains linear infinite chains of repeating (AlF3) units, classifying it as a so-called ino-fluoro-aluminate.

Classification of ThermessaiteHide

Approval Year:

C : Complex halides
G : Aluminofluorides with CO3, SO4, PO4

Physical Properties of ThermessaiteHide

colourless to white
Hardness Data:
Could not be measured
None Observed
None observed
2.77(2) g/cm3 (Measured)    2.790 g/cm3 (Calculated)
from flotation at 25°C in bromoform-chloroform

Chemical Properties of ThermessaiteHide


Crystallography of ThermessaiteHide

Crystal System:
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:
Cell Parameters:
a = 10.81 Å, b = 8.336 Å, c = 6.822 Å
a:b:c = 1.297 : 1 : 0.818
Unit Cell V:
614.75 ų (Calculated from Unit Cell)
Prismatic with {110} and the pinacoid {100} as the dominant forms, terminated by minor {111}.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
6.631 (70)
5.429 (14)
3.317 (28)
2.983 (100)
2.702 (82)
2.648 (14)
2.208 (30)
1.712 (58)

Type Occurrence of ThermessaiteHide

General Appearance of Type Material:
sharp translucent crystals up to 0.25 mm
Place of Conservation of Type Material:
Referece Collection of Dipartimento di Chimica Strutturale e Stereochimica Inorganica of Universita degli Studi di Milano, Milan, Italy
Geological Setting of Type Material:
An altered pyroclastic breccia in active medium- to high-temperature fumaroles at the rim of La Fossa crater.
Associated Minerals at Type Locality:

Synonyms of ThermessaiteHide

Other Language Names for ThermessaiteHide

Simplified Chinese:氟铝钾矾

Common AssociatesHide

Associated Minerals Based on Photo Data:
Vlodavetsite1 photo of Thermessaite associated with Vlodavetsite on mindat.org.
Cossaite1 photo of Thermessaite associated with Cossaite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

3.CG.05Stenonite(Sr,Ba,Na)2Al(CO3)F5Mon. 2/m
3.CG.10Chukhrovite-(Ce)Ca3(Ce,Y)[F|SO4|(AlF6)2] · 10H2OIso.
3.CG.10Chukhrovite-(Y)Ca3(Y,Ce)[F|SO4|(AlF6)2] · 10H2OIso.
3.CG.10MeniayloviteCa4[F|SO4|SiF6|AlF6] · 12H2OIso. m3 (2/m 3) : Fd3
3.CG.10Chukhrovite-(Nd)Ca3(Nd,Y)Al2(SO4)F13·12H2OIso. m3 (2/m 3) : Fd3
3.CG.15CreediteCa3SO4Al2F8(OH)2 · 2H2OMon. 2/m : B2/b

Fluorescence of ThermessaiteHide

none observed under both short- and long-wave

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for ThermessaiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Demartin, F., Gramacciolo, C.M., Campostrini, I. & Orlandi, P. (2008): Thermessaite, K2[AlF3|SO4], a new ino-aluminofluoride-sulfate from La Fossa crater, Vulcano, Aeolian Islands, Italy. Canadian Mineralogist 46, 693-700.

Internet Links for ThermessaiteHide

Localities for ThermessaiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • North Rhine-Westphalia
    • Aachen
      • Alsdorf
Witzke, T., de Wit, F., Kolitsch, U. and Blaß, G. (2015): Mineralogy of the Burning Anna I Coal Mine Dump, Alsdorf, Germany. Chapter 7, pp. 203-240, in: Stracher, G. B., Prakash, A. and Sokol, E. V.: Coal and Peat Fires: A Global Perspective, Volume 3: Case Studies - Coal Fires, Elsevier, 786 pp.
Italy (TL)
  • Sicily
    • Messina Province
      • Eolie Islands (Aeolian Islands)
        • Lipari
          • Vulcano Island
Demartin, F., Gramacciolo, C.M., Campostrini, I. & Orlandi, P. (2008): Thermessaite, K2[AlF3|SO4], a new ino-aluminofluoride-sulfate from La Fossa crater, Vulcano, Aeolian Islands, Italy. Canadian Mineralogist 46, 693-700.
Mineral and/or Locality  
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