Whewellite

Whewellite is a mineral, hydrated calcium oxalate, formula CaC2O4·H2O. Because of its organic content it is thought to have an indirect biological origin and this is supported by it being found in coal and sedimentary nodules. However, it has also been found in hydrothermal deposits where a biological source appears improbable. For this reason it can be classed as true mineral.
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(n.)
Calcium oxalate, occurring in colorless or white monoclinic crystals.
  

General Information:
 Chemical Formula:
Ca(C2O4)·(H2O)
 Composition:
(Molecular Weight = 146.11 gm)
Calcium 27.43 % Ca
Hydrogen 1.38 % H 
Carbon 16.44 % C 
Oxygen 54.75 % O 
 Empirical Formula:
CaC2O4·(H2O)
 Environment:
The mineral is deposited from low temperature hydrothermal solutions which have come into contact with carboniferous lithologies, releasing methane, such as in graphitic schists or, primarily, from areas surrounding coa
 IMA Status:
Approved IMA 1962
 Locality:
The classic locality occurs in the anthracite deposits of the Doehlener Basin of Freital and Burgk, where clear crystals of up to 2 cm, mostly twinned, are found in association with ca lcite, pyrite, markesite, limonite and ga
 Name Origin:
Named after the British mineralogist, crystallographer and natural philosopher William Whewell (1794-1866),
Physical Properties:
 Cleavage:
[101] Good, [010] Good, [110] Good
 Color:
brownish, colorless, gray, yellow, or yellow brown.
 Density:
2.21 - 2.23, Average = 2.21
 Diaphaniety:
Transparent to translucent
 Habits:
Tabular - Form dimensions are thin in one direction., Granular - Generally occurs as anhedral to subhedral crystals in matrix., Prismatic - Crystals Shaped like Slender Prisms (e.g. t ourmaline).
 Hardness:
2.5-3 - Finger Nail-Calcite
 Luminescence:
Fluorescent.
 Luster:
Vitreous - Pearly
 Streak:
white
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