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].
The presence of oxalates can suggest a biological attack due to fungal species that can reprecipitate secondary carbonates and biomineralize hyphae with both calcite and
whewellite [29].
Tielens et al., "Hyperoxaluria is related to
whewellite and hypercalciuria to weddellite: what happens when crystalline conversion occurs?," Comptes Rendus Chimie, vol.
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].
(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.
The generalized succession scheme according to Kaspar (1939) is (from oldest to youngest): older carbonates (siderite, ankerite, dolomite), barite, sulphides,
whewellite, nacrite, young carbonates (calcite) and secondary minerals (sulphates).
Upon analysis, the stone was reported as a
whewellite stone.
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).