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Whewellite
Current inventory:  0 gems
 

Chemistry:  CaC₂O₄·(H₂O)  [Hydrated Calcium Oxalate]

Discovered in 1852;   IMA status: Valid (pre-IMA; Grandfathered).
Named after the British mineralogist, crystallographer and natural philosopher William Whewell (1794-1866), professor of mineralogy at Cambridge.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

9/A.01-10

Nickel-Strunz 10th Ed. ID:

10.AB.45

10 : ORGANIC COMPOUNDS
A : Salts of organic acids
B : Oxalates

Related to:

Whewellite - Wheatleyite Series

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Equant to short primatic crystals, typically distorted, to 23 cm; cleavable massive.

Twinning:

Very common on [101] as twin and contact plane, with or without re-entrants.

Physical Properties

Cleavage:

[101] Very Good, [010] Imperfect, [110] Indistince, [001] Imperfect

Fracture:

Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

2.5 - 3.0

Density:

2.21 - 2.23 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Soluble in acids. Insoluble in water.

Optical Properties

Color:

Colorless, Gray, Yellow, Yellow Brown, Brownish

Transparency:

Transparent to Translucent

Luster:

Vitreous, Pearly on some cleavages

Refractive Index:

1.489 - 1.650  Biaxial ( + )

Birefringence:

0.1600

Dispersion:

None; r < v

Pleochroism:

None

Other:

Soluble in acids. Insoluble in water.

Occurances

Geological Setting:

Of uncommon occurrence as a low-temperature primary hydrothermal mineral in carbonate-sulfide veins, geodes, or septarian nodules; may be associated with coal measures or formed by oxidation of organic material in surrounding rocks; in some uranium deposits.

Common Associations:

Barite, Calcite, Pyrite, Sphalerite, Weddellite, waxy hydrocarbons

Type Locality:

Originally described from an unknown locality.

Year Discovered:

1852

View mineral photos:

Whewellite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Whewellite is a very rare and unusual mineral and an extremely rare gem. It is a crystalline organic mineral similar to Amber except that Amber lacks a crystalline structure. It is up for debate whether Whewellite is actually a mineral since it has an organic connection in its formation. Whewellite is formed by the oxidation of organic material in coal seams and sedimentary nodules and concretions. Other than this organic connection, Whewellite can be consided a legitimate mineral because it meets the basic criteria for minerals: it is naturally formed; a crystalline solid; composed of a set chemical formula; and is formed with no direct biological connection. Whewellite gems are extremely rare, very small, have little to no dispersion, and offer little but their rarity.

Whewellite crystal sources include Zwickau, Germany; Cavnic, Romania; Dal’negorsk, Primorskiy Kray, Russia; near Biggs, Sherman County, Oregon, USA; near Moab San Juan County, Utah, USA.
 

  
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