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Witherite
Current inventory:  1 gem
 

   
Witherite is named after Dr. William Withering (1741-1799), English physician and mineralogist, who first noted the material.

Discovered in 1790;   IMA status: Valid (pre-IMA; Grandfathered).

Chemistry

Chemical Formula:

Ba(CO₃)

Barium Carbonate

Molecular Weight:

197.34 gm

Composition: 

Classification

Mineral Classification:

Carbonates

Strunz 8th Ed. ID:

5/B.04-30

Nickel-Strunz 10th Ed. ID:

5.AB.15

5 : CARBONATES (NITRATES)
A : Carbonates without additional anions, without H₂O
B : Alkali-earth (and other M²⁺) carbonates

Related to:

Aragonite Group. Strontianite - Witherite Series.

Synonyms:

Aerated Barytes, Barolite, Barolite (of Kirwan), Sulphato-Carbonate of Baryta, Viterite

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Pseudohexagonal dipyramidal due to repeated twinning, short prismatic to elongated, other faces commonly rough and horizontally striated, to 12 cm. May be botryoidal to spherical, columnar fibrous, granular, massive.

Twinning:

On [110], universal

Physical Properties

Cleavage:

[010] Distinct, [110] Imperfect

Fracture:

Subconchoidal to Uneven

Tenacity:

Brittle

Moh's Hardness:

3.0 - 3.5

Density:

4.289 - 4.293 (g/cm³)

Luminescence:

Short Wave UV = Bluish White with phosphorescence (Green and Yellow in material from England), Long Wave UV = Bluish White with phosphorescence (Yellowish in material from England); effervesces in dilute HCl solutions; Fluoresces in X-rays.

Radioactivity:

Not Radioactive

Health Warning:

CAUTION: Barium Carbonate is toxic if ingested. Handling of Witherite is not a major cause of concern as long as you avoid breathing in dust and you wash your hands after handling.

Other:

Soluble in dilute HCl

Optical Properties

Color:

Colorless, Milky white, Grayish white, Pale yellowish white, Pale brownish white

Transparency:

Subtransparent to Translucent

Luster:

Vitreous (Glassy)

Refractive Index:

1.529 - 1.677  Biaxial ( - )

Birefringence:

0.1480

Dispersion:

Very Weak; r > v

Pleochroism:

None

Occurances

Geological Setting:

Usually in minor amounts in low-temperature hydrothermal veins, typically an alteration product of barite; may be of anoxic sedimentary origin, barium supplied by volcanic hot-spring activity; uncommon in coal measures.

Common Associations:

Barite, Calcite, Fluorite, Galena

Common Impurities:

Ca, Sr

Type Locality:

Brownley Hill Mine (Bloomsberry Horse Level), Nenthead, Alston Moor District, North Pennines, North and Western Region (Cumberland), Cumbria, England, UK

Year Discovered:

1790

View mineral photos:

Witherite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Witherite is a rare member of the Aragonite group of minerals that also includes Aragonite and Cerussite. Witherite is very rarely faceted because it is soft, fragile and difficult to polish. It is an interesting mineral in that its crystals always form twins. All members of the Aragonite group can form twins, but Witherite is one member that always forms twins! Witherite gems typically have a pearly luster or internal "sleepiness" similar to Prehnite.

Notable occurances of Witherite are Cave-in-Rock, Hardin County, Illinois, USA; Alston Moor, Cumberland and Durham, England; Thunder Bay area, Ontario, Canada.
 

  
Witherite gems for sale: