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Thénardite

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Louis Jacques Thénard
Formula:
Na2SO4
System:
Orthorhombic
Colour:
Colourless, very light ...
Hardness:
2½ - 3
Name:
Named after Louis Jacques Thénard (1777-1857), Professor of Chemistry, University of Paris (France).
Originally named thenardite; renamed thénardite in 2014 (IMA 14-A).
Five polymorphs known.
May occur as a dehydration product of mirabilite.

Classification of Thénardite

Renamed approved 2014
7.AC.25

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
A : Sulfates (selenates, etc.) without additional anions, without H2O
C : With medium-sized and large cations
28.2.3.1

28 : ANHYDROUS ACID AND NORMAL SULFATES
2 : A2XO4
25.1.1

25 : Sulphates
1 : Sulphates of the alkali metals and ammonium
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First Recorded Occurrence of Thénardite

Year of Discovery:
1826
Geological Setting of First Recorded Material:
Salt Lake.

Occurrences of Thénardite

Geological Setting:
Lakes and playas in arid regions; as efflorescences on soils in arid areas, and in caliche. Also occurs around volcanic fumaroles mixed with alkali halides and sulphates and as an incrustation on recent lavas.

Physical Properties of Thénardite

Vitreous, Resinous
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Colourless, very light grey, light brown; colourless in transmitted light
Hardness (Mohs):
2½ - 3
Tenacity:
Brittle
Cleavage:
Perfect
On {010} perfect; on {101} fair; on {100} incomplete
Fracture:
Irregular/Uneven, Hackly
Density:
2.664 g/cm3 (Measured)    2.674 g/cm3 (Calculated)

Crystallography of Thénardite

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:
Fddd
Cell Parameters:
a = 5.86Å, b = 12.3Å, c = 9.82Å
Ratio:
a:b:c = 0.476 : 1 : 0.798
Unit Cell Volume:
V 707.81 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Crystals dipyramidal {111} with minor truncations; tabular {010} rough and striated, and {101} present as large faces; prismatic [100], rare. Pulverulent crusts, efflorescences.
Twinning:
On {110} common, yielding cruciform groups. Also on {011}, yielding twins rather similar to gypsum "butterfly" twins.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Thénardite

Type:
Biaxial (+)
RI values:
nα = 1.471 nβ = 1.477 nγ = 1.484
2V:
Measured: 83° , Calculated: 86°
Max Birefringence:
δ = 0.013
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
none

Chemical Properties of Thénardite

Formula:
Na2SO4
Essential elements:
All elements listed in formula:

Relationship of Thénardite to other Species

7.AC.05VanthoffiteNa6Mg(SO4)4
7.AC.08Pyracmonite(NH4)3Fe(SO4)3
7.AC.10Efremovite(NH4)2Mg2(SO4)3
7.AC.10LangbeiniteK2Mg2(SO4)3
7.AC.10ManganolangbeiniteK2Mn2(SO4)3
7.AC.15YavapaiiteKFe(SO4)2
7.AC.15EldfelliteNaFe3+(SO4)2
7.AC.20Godovikovite(NH4)Al(SO4)2
7.AC.20Sabieite(NH4)Fe3+(SO4)2
7.AC.30MetathenarditeNa2SO4
7.AC.35Aphthitalite(K,Na)3Na(SO4)2
25.1.2MatteucciteNaHSO4 · H2O
25.1.3MirabiliteNa2SO4 · 10H2O
25.1.4ArcaniteK2SO4
25.1.5MercalliteKHSO4
25.1.6MiseniteK8H6(SO4)7
25.1.7Aphthitalite(K,Na)3Na(SO4)2
25.1.8Mascagnite(NH4)2SO4
25.1.9Letovicite(NH4)3H(SO4)2
25.1.10Ammonioalunite(NH4)Al3(SO4)2(OH)6

Other Names for Thénardite

Name in Other Languages:
Simplified Chinese:无水芒硝
Spanish:Thenardita
Traditional Chinese:無水芒硝

Other Information

Thermal Behaviour:
Melting Point = 883° C.
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 Thénardite

Reference List:
Casaseca J.L., (1826), Annales de chimie et de physique, Paris: 32, 308.

Casaseca J.L., (1826) Annals of Philosophy, London: 12: 313.

Breithaupt, A. (1832) Vollständige Characteristik etc., 2nd. Ed.: 33 (as Anhydrisches Natronsulfat).

Scacchi (1855) Mem. Incend. Vesuvius, Naples (as Pyrotechnite).

Des Cloizeaux (1857) Annales des mines: 11: 318.

Baerwald (1882) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 6: 36.

Dana, E.S. (1892) System of Mineralogy, 6th. Edition, New York: 895.

Görgey (1910) Mineralogische und petrographische Mitteilungen, Vienna: 29: 202.

Larsen, E.S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 143.

Goldschmidt, V. (1922) Atlas der Krystallformen. 9 volumes, atlas, and text, vol. 8: 126.

Kracek (1921) Journal of Physical Chemistry: 33: 1281, 1304.

Cole (1926) Canada, Mines Branch, Ottawa, no. 646.

Doelter, C. (1926) Handbuch der Mineral-chemie (in 4 volumes divided into parts): 4[2]: 35 (see Jänecke in).

Hintze, Carl (1929) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3B]: 2679.

Kracek (1929) Journal of Physical Chemistry: 33: 1281.

Kracek and Gibson (1929) Journal of Physical Chemistry: 33: 1304.

Zachariasen and Ziegler (1932) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 81: 92.

Hill and Wills (1938) Journal of the American Chemical Society: 60: 1647.

Spencer (1944) Mineralogical Magazine: 27: 29.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 404-407.

Canadian Mineralogist (1975): 13: 181-187.

Neues Jahrbuch für Mineralogie, Monatshefte (1978): 408.

Acta Chemica Scandinavica:: 27: 814-822.

Internet Links for Thénardite

Specimens:
The following Thénardite specimens are currently listed for sale on minfind.com.

Localities for Thénardite

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.
Mineral and/or Locality  
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