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Formula: Ca(C2O4).H2O
Organic compound
Specific gravity: 2.21 to 2.23 measured, 2.22 calculated
Hardness: 2½ to 3
Colour: White, yellow, brown, colourless; colourless in transmitted light
Solubility: Soluble in acids. Insoluble in water.
Environments
Sedimentary environments
Hydrothermal environments
Whewellite is a rare mineral in carbonate-sulphide veins; it also occurs in geodes, or septarian nodules; it is
associated with coal measures and surrounding rocks with organic material; it is found in some uranium deposits; it
occurs as microscopic crystals in living plant cells and as calculi or as a sediment in the human urinary tract; it is
also described as a product of fungal activity and is also formed by lichen on various rocks.
Common associates include baryte,
calcite, pyrite,
sphalerite and weddellite
(Mindat,HOM).
Whewellite is ordinarily of organic origin, but it is also deposited from low-temperature
primary hydrothermal solutions which have come into contact with
carboniferous lithologies, releasing methane, such as in graphitic
schists or, primarily, from areas surrounding coal measures
(Webmin, Dana).
Research has confirmed that caoxite transforms into whewellite by
dehydration and not via weddellite
(AM 90.1469).
The crystallisation of the calcium oxalates weddellite and whewellite
by interaction of calcite marble
with the fungus Aspergillus niger, is one of the most active stone destructors
(AM 100.2559-2565).
Localities
The type locality is not known.
At the Kladno District, Central Bohemian Region, Czech Republic, whewellite occurs with lignite coal
(Dana).
At the Sylvester Mine, Urbeis, Sélestat-Erstein, Bas-Rhin, Grand Est, France, whewellite occurs in veins with
tetrahedrite, carbonates and quartz
(Dana).
At Freiberg, Mittelsachsen, Saxony, Germany, whewellite occurs in a vein with
calcite and silver
(Dana).
At Burgk, Freital, Sächsische Schweiz-Osterzgebirge, Saxony, Germany, whewellite occurs in large crystals in a
coal seam
(Dana).
On the Yareg River, Timan Range, Komi Republic, Russia, whewellite occurs in
calcite veins in shale
(Dana).
At Havre, Hill county, Montana, USA, a single crystal of whewellite was found in a fossiliferous, septarian
limestone concretion in marine
shale; several limestone
concretions 1 to 4 feet in diameter are exposed here. The enclosing
shale is locally
bentonitic and gypsiferous.
Yellow to brownish-yellow calcite in irregular and interconnecting veins
characterises the marine septarian concretions of this region. Although minerals other than
calcite are extremely rare in the concretions,
baryte, gypsum, and
quartz have been collected from several of them.
The whewellite-bearing concretion was about 2 feet in diameter. The septarian vein development ranges in width
from about 3 inches down to barely perceptible fractures lined with calcite.
In contact with the rock of the concretion and separating it from the coarse
calcite of the septarian veins is a thin layer of fibrous
calcite that fluoresces bright yellow in shortwave UV. The whewellite
crystal is perched on coarse pale yellow, non-fluorescent calcite crystals,
and its surface is coated by a thin incrustation of very fine-grained
aragonite and pink calcite
(AM 39.208-214).
At the Huron Shale concretions, Huron River, Huron county, Ohio, USA, concretions one to three feet in diameter are
quite common and many are septarian
(AM 51.228-229).
The bedrock in the region is largely a greyish black, fissile shale,
locally fossiliferous. It was apparently deposited under stagnant ocean bottom conditions, as it contains considerable
carbonaceous material.
The specimens are on two kinds of matrix. One is a dark grey crystalline
calcite, and the other is a light grey mixture of
dolomite and calcite. In both the
matrices the whewellite is in white, translucent masses with numerous inclusions, perhaps fluid
filled. A thin selvage of friable calcite, locally showing minute, simple
rhombohedral crystals, surrounds the whewellite masses. Much of the whewellite is deeply etched and
permeated along cleavage cracks with thin films of calcite, which is apparently
an alteration product of the whewellite. The calcite fluoresces a cream
yellow colour. A few of the whewellite specimens are permeated with
calcite which shows a rose pink fluorescence, sometimes very bright, in long
wave UV. Several other minerals, including baryte,
dolomite, iron-bearing
dolomite and pyrite, are associated
with the whewellite; all are found between the whewellite masses and the concretion matrix.
Pyrite occurs as minute, stalactitic masses in pockets in the
dolomite and as tiny crystalline grains in the whewellite and
baryte
(AM 53.455-463).
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