weddellite


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weddellite

[wə′de‚līt]
(mineralogy)
CaC2O4·2H2O A colorless to white or yellowish-brown to brown, tetragonal mineral consisting of calcium oxalate dihydrate.
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The two most commonly occurring mineral forms of CaOx are whewellite (Ca[C.sub.2][O.sub.4].[H.sub.2]O) and weddellite (Ca[C.sub.2][O.sub.4].2[H.sub.2]O).
Calcium oxalate is found in the majority of kidney stones and exists in the form of CaOx monohydrate (COM, termed as mineral names: whewellite, Ca[C.sub.2][O.sub.4].[H.sub.2]O), and CaOx dihydrate (COD, weddellite, Ca[C.sub.2][O.sub.4].2[H.sub.2]O), or as a combination of both which accounts for greater than 60% [33].
Tielens et al., "Hyperoxaluria is related to whewellite and hypercalciuria to weddellite: what happens when crystalline conversion occurs?," Comptes Rendus Chimie, vol.
However, some mineral compounds were also detected, namely, silica (SiO2) and weddellite (Ca[C.sub.2][O.sub.4]-2 [H.sub.2]O) which is a form of calcium oxalate.
The frequency of the minerals identified was: fifteen samples of whewellite Ca[C.sub.2][O.sub.4].[H.sub.2]O; eleven huntite samples, nine of which also contained calcite CaC[O.sub.3]; five dolomite samples MgCa[(C[O.sub.3]).sub.2]; two samples of the dihydrate of calcium oxalate, weddellite, Ca[C.sub.2][O.sub.4].2[H.sub.2]O, which came from the walls and ceiling of a rock shelter in the Mitchell Plateau; and there were only single samples of antigorite [Mg.sub.3][Si.sub.2][O.sub.5][(OH).sub.4], a serpentine mineral, and the clay illite (K,[H.sub.30])[Al.sub.2][Si.sub.3]Al[O.sub.10][(OH).sub.2].
Urinary stones maybe composed of calcium oxalate monohydrate (COM, whewellite), calcium oxalate dihydrate (COD, weddellite), carbonate apatite (CA, dahllite), ammonium urate, magnesium ammonium phosphate (PAM, Struvite), calcium hydrogen phosphate dihydrate (brushite), uric acid (AU0 anhydrous form and AU2 dihydrate form, uricite) and its salts, cystine, xanthine, 2,8-dihydroxyadenine, and drugs [3].
(5,6) In contrast, the only previous study to have addressed renal stone composition in Iran showed that the most common components were whewellite (81.5%), weddellite (40.7%), apatite (69%), and ammonium acid urate.
Gypsum CaS[O.sub.4] x 2[H.sub.2]O presented vibrations at 3693, 1618 and 1089 [cm.sup.-1] from Bogota; at 3647, 1628, 1076 and 714 [cm.sup.-1] from Villa de Leyva, at 3651 cm-1 from Barichara; weddellite Ca[C.sub.2]O x [H.sub.2]O at 1618 and 779 [cm.sup.-1] from Bogota; at 1628 and 779 [cm.sup.-1] from Villa de Leyva and Barichara; calcite/ aragonite (CaC[O.sub.3]) at 1425 and 876 [cm.sup.-1] for Bogota; at 1796, 1429, 874 and 714 [cm.sup.-1] from Villa de Leyva, at 1441 and 874 [cm.sup.-1] from Barichara.
Calcium oxalate (CaOx) in the urine presents as octahedral crystals of weddellite ("post envelopes") of sizes from 5 to 15um achieving 50-100 [micro]m in some cases.
Crystalline calcium oxalates have been found in two different hydration states in plants, either as the monohydrate (whewellite, Ca[C.sub.2][O.sub.4] x [H.sub.2]O) or as the dihydrate (weddellite, Ca[C.sub.2][O.sub.4] x 2[H.sub.2]O) (Arnott 1982, Monje & Baran 2002b, Franceschi & Nakata 2005, Baran & Monje 2008).
The components are as follows: ammonium hydrogen urate (AMUR), brushite (BRUS), carbonate apatite (CARB), cystine (CYST), struvite (STRU), uric acid (URIC), weddellite (WEDD), and whewellite (WHEW; Table 1).