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Thénardite
Current inventory:  0 gems
 

Thenardite

Chemistry:  Na2SO4  [Sodium Sulfate]

Discovered in 1826;   IMA status: Valid (pre-IMA; Grandfathered).
Thénardite is named in honor of Professor Louis Jacques Thénard (1777–1857), French chemist, University of Pierre and Marie Curie, Paris, France.

 

Classification

   

   

Mineral Classification:

Sulfates

Strunz 8th Ed. ID:

6/A.07-10

Nickel-Strunz 10th Ed. ID:

7.AC.25

 

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
A : Sulfates (selenates, etc.) without additional anions, without H
2O
C : With medium-sized and large cations

Related to:

Thénardite - Mascagnite Series

 

 

Crystal Data

   

   

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals dipyramidal {111}, or tabular {010} with large {101}, rarely prismatic along [100], to 20 cm; as pulverulent crusts and efflorescences

Twinning:

On {110}, commonly forming cruciform groups; as crude butterflylike twins on {011}

 

 

Physical Properties

   

 

Cleavage:

[010] Perfect, [101] Fair, [100] Interrupted

Fracture:

Splintery, Uneven to Hackly

Tenacity:

Somewhat Brittle

Hardness (Mohs):

2.5 - 3.0

Density:

2.664 - 2.700 (g/cm3)

Luminescence:

Fluorescent; SW UV = white, LW UV = yellow-green

Radioactivity:

Not Radioactive

Other:

Easily soluble in water

 

 

Optical Properties

   

   

Color:

Colorless; Grayish White, pale Yellow, Yellow-Brown, Reddish due to inclusions

Transparency:

Transparent to Translucent

Luster:

Vitreous to Resinous

Refractive Index:

1.471 - 1.484  Biaxial ( + )

Birefringence:

0.0013

Dispersion:

Weak to None; r > v

Pleochroism:

None

 

 

Occurances

   

   

Geological Setting:

Typically in lacustrine (salt and soda lake) evaporite deposits in arid regions, also as crusts and efflorescences, which may be ephemeral, in a wide range of geologic environments; as precipitates around fumaroles.

Common Associations:

Blödite, Epsomite, Glauberite, Gypsum, Halite, Mirabilite, Natron

Type Locality:

Espartinas Salt Lake, Aranjuez, Madrid, Spain

Year Discovered:

1826

View mineral photos:

Thénardite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Thénardite is a rare sulfate mineral that is rarely found as crystals large enough for faceting. It is one of several arid region, non-marine evaporate sulfate minerals and is associated with other minerals that form in the deposits of playa lakes. Thénardite is readily water soluble and should be stored carefully.

There are numerous minor occurrences of Thénardite but rarely in thick beds or as large crystals. Two notable localities for relatively large crystals are from Searles Lake, San Bernardino County, California, USA and Bärenstein Quarry, Niederschlag, Oberwiesenthal, Erzgebirge, Saxony, Germany.
 

  
Thénardite gems for sale:

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