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Glauberite
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Glauberite is named in allusion to Glauber’s Salt (Na₂SO₄), the synthetic equivalent of the dominant chemical component, named for Johann Rudolf Glauber (1604–1668), German alchemist.

Discovered in 1808;   IMA status: Valid (pre-IMA; Grandfathered).

Chemistry

Chemical Formula:

Na₂Ca(SO₄)₂

Sodium Calcium Sulfate

Molecular Weight:

278.18 gm

Composition: 

Classification

Mineral Classification:

Sulfates

Strunz 8th Ed. ID:

6/A.08-40

Nickel-Strunz 10th Ed. ID:

7.AD.25

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
A : Sulfates (selenates, etc.) without additional anions, without H₂O
D : With only large cations

Related to:

n/a

Synonyms:

Glauber's Salt

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Crystals, to 10 cm, tabular on {001}, prismatic along [101] with dominant {111} or along [001] with dominant {110}, or dipyramidal with dominant {111}, {110}; {001} and {111} may be striated k mutual intersections, yielding steplike terminations.

Twinning:

None

Physical Properties

Cleavage:

[001] Perfect, [110] Imperfect

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

2.5 - 3.0

Density:

2.75 - 2.85 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Slightly saline taste; powdery surface alteration in humid environments, leaching Na₂SO₄ and leaving gypsum. Very slightly soluble in water.

Optical Properties

Color:

Gray, pale Yellow, Colorless; Colorless in transmitted light

Transparency:

Transparent to Translucent

Luster:

Vitreous to Waxy; Pearly on {001} cleavage surfaces

Refractive Index:

1.507 - 1.536  Biaxial ( - )

Birefringence:

0.0220

Dispersion:

Strong; r > v

Pleochroism:

X = colorless; Y = colorless

Occurances

Geological Setting:

A common constituent of continental and marine evaporite deposits; as sublimates around fumaroles; in mineral-filled cavities in basaltic lava; in nitrate deposits in arid climates.

Common Associations:

Anhydrite, Gypsum, Halite, Mirabilite, Polyhalite, Thénardite (evaporites); Thénardite, Sassolite (fumaroles); Blödite, Thénardite (nitrate deposits).

Co-type Localities:

El Castellar mine, Villarrubia de Santiago, Ocaña, Toledo, Castile-La Mancha, Spain
Los Castilletes mine, Villarrubia de Santiago, Ocaña, Toledo, Castile-La Mancha, Spain

Year Discovered:

1808

View mineral photos:

Glauberite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Glauberite is named for the salt that helps compose its chemistry called "Glauber's salt" which is named after German alchemist Johann Rudolf Glauber (1604–1668). It is a mineral that forms in saline environments with other evaporite minerals such as halite, Gypsum, Calcite and Thénardite.Glauberite is a relatively rare mineral and an extremely rare gem. Glauberite gems are curiosities for collectors of the very rare and unusual.

Glauberite is often pseudomorphed or cast by other minerals. Pseudomorph means "false shape" and occurs when a mineral is replaced by another mineral at such a very slow rate, essentially atom by atom, that no deterioration of the original shape of the crystal occurs. The resulting crystal retains the shape of the original mineral crystal but has the composition of the new mineral. A cast occurs when other minerals grow over an existing crystal then the original crystal completely dissolves, leaving a cast of the shape of the original crystal. The crystal habit, or shape, of a Glauberite crystal is unique enough that its pseudomorphs and casts can often be identified as being from a Glauberite crystal. Glauberite is soluble in water which is why it often creates casts.

Notable occurrences of Glauberite include Saline Valley, Inyo County and Searles Lake, San Bernardino County, California; Great Salt Lake, Utah, Texas, New Mexico and Verde Valley, Arizona, USA; Strassfurt, Germany; Russia; Kenya; Chile; Toledo, Spain; Salzburg, Austria; France; Canada; Sicily and India. Pseudomorphs and casts come from many of the previously mentioned localities and from Paterson and Great Notch, New Jersey, USA.
 

  
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