Weddellite
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| Weddellite | |
|---|---|
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| General | |
| Category | Mineral |
| Chemical formula | Oxalate(Oxalic acid) (Calcium oxalate dihydrate CaC2O4·2H2O ) |
| Identification | |
| Color | Yellowish brown |
| Crystal habit | eight-face bi-pyramid (typical) |
| Crystal system | Tetragonal |
| Twinning | yes |
| Cleavage | OUI |
| Fracture | Conchoidal |
| Mohs Scale hardness | 4 |
| Luster | Vitreous (Glassy) |
| Refractive index | 1.52-1.54 - DR +0.009 (B-G interval) |
| Streak | White |
Weddellite (CaC2O4·2H2O) is a mineral form of calcium oxalate named for occurrences of millimeter-sized crystals found in bottom sediments of the Weddell Sea, off Antarctica. Occasionally, weddellite partially dehydrates to whewellite, forming excellent pseudomorphs of grainy whewellite after weddellite's short tetragonal dipyramids.
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[edit] Structural properties
The weddelite or calcium oxalate di-hydrate crystallizes in the tetragonal system. The classic crystal shape is the eight-face bi-pyramid. In bright field microscopy, the weddelite crystals are recognized easily by their shape that reminds a mail envelope. More complex shapes of weddelite are possible. The dumbbell shape is not rare. The former has no precise angles or sides. This form is, in reality, a microcrystalline agglomerate that takes the shape of a biconcave disc. Weddelite crystals are poorly birefringent and do not show any interference pattern under polarized light.
[edit] Biological role
Weddelite crystals are usually of little clinical value. Many specimens develop weddelite crystals on standing. Together, apatite, whewellite, and weddellite are probably the most common urinary stones.
[edit] Varieties and related minerals
Natroxalate, Whewellite, Caoxite, Novgorodovaite, Oxammite, Glushinskite, Humboldtine, Minguzzite, Zhemchuzhnikovite, Stepanovite, Moolooite, Wheatleyite, Coskrenite
[edit] References
- Weddellite. Weddellite: Weddellite mineral data. Retrieved on June 23, 2005.
- Weddellite. MINERALOGY OF KIDNEY STONES. Retrieved on June 21, 2005.
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