ChemInform Abstract: THERMOCHEMICAL, CRYSTALLOGRAPHIC AND INFRARED STUDIES ON CALCIUM COPPER HYDROXIDE CHLORIDE HYDRATES

Abstract

Das bei der Cu‐Korrosion in NH3‐haltiger 1 N CaCl2‐Lösung in Gegenwart von O2 entstehende Hydroxychloridhydrat (I) kristallisiert tetragonal (P42**) mit Z=4.

Centennialite, CaCu3(OH)6Cl2.nH2O,n≈ 0.7, a new kapellasite-like species, and a reassessment of calumetite

“…Ahmeek (see figs 50 and 144 of Mineralogy of Michigan; Heinrich and Robinson, 2004), Quincy, White Pine, Mohawk and Centennial mines, where "it often occurs with calumetite, which it greatly resembles." It is proposed, on the basis of X-ray and infrared data (unpublished work of B. C. Cornilsen, cited in Mineralogy of Michigan) that this unknown mineral corresponds to the compound of Erdös et al (1981); however, "…that it is only found in small amounts, intimately mixed with other phases [therefore] making it nearly impossible to characterize." Further unpublished work since made available to these authors has also highlighted the occurrence of centennialite (in association with calumetite) from those mines listed above and the Franklin Jr. mine (Brandes and Robinson, 2002).…”

“…Through inspection of powder X-ray diffraction patterns of samples from these minute specimens, it became apparent that the samples were not calumetite, but were an intimate admixture of minor paratacamite and a material most similar to JCPDS 32-1258 † , a hexagonal, basic calcium-copper hydroxychloride monohydrate, Cu 3 (OH) 6 CaCl 2 •H 2 O, a = 6.66 Å, c = 5.81 Å, prepared by Erdös et al (1981). Erdös et al (1981) also report that their compound is one of a series of basic hydroxychlorides reported by Feitknecht (1949) and Oswald and Feitknecht (1964), most recently cited through their relation to the new descriptions of kapellasite (Cu 3 Zn(OH) 6 Cl 2 ) (Krause et al, 2006), herbertsmithite (Braithwaite et al, 2004) and haydeeite (Cu 3 Mg(OH) 6 Cl 2 ) (Schlüter and Malcherek, 2007). Later studies have further developed the crystallization of that same compound, on an industrial scale (Lubej et al, 2004), where it appears (as do other related basic copper salts) as active ingredients of a range of contact fungicides/herbicides akin to Bordeaux mixture.…”

“…Later studies have further developed the crystallization of that same compound, on an industrial scale (Lubej et al, 2004), where it appears (as do other related basic copper salts) as active ingredients of a range of contact fungicides/herbicides akin to Bordeaux mixture. We became more intrigued because Erdös et al (1981) also reported a more hydrated Cu 4 CaCl 2 (OH) 8 •3.5H 2 O compound (JCPDS 32-1257) that was indexed as primitive tetragonal (a = 9.44, c = 15.077 Å) and commented upon as being calumetite-like. When heated to 165°C, this compound is also reported to form Cu 3 (OH) 6 CaCl 2 •H 2 O, apparently the same phase that dominated our natural specimens.…”

“…In designing such a system, we might then require the largest difference between non-magnetic M 2+ and Cu cations that will still afford crystallization in this structure type, in order to give the maximum interlayer gap and minimize possible cation site mixing. The compound used by Erdös et al (1981) was Ca-containing and Ca has an ionic radius significantly larger (six-coordinated Ca 2+ = 1.00 Å) than other atacamite, or kapellasite M 2+ cations (e.g. Mg = 0.72 Å, Zn = 0.75 Å, Mn 2+ = 0.83 Å (high spin); cf.…”

New Mineral Names*,†

“…The atomic ratio Ca:Cu:Cl ∼ 1:3:2 for all three cotypes. As more accurate data pertaining specifically to centennialite was not obtained on the natural samples, analyses were also performed on synthetic material with X-ray control to ensure the phase analyzed is identical to both centennialite and its synthetic analog (Erdös et al 1981). A combination of combustion analysis, ion chromatography, inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectroscopy analyses resulted as (wt%): Ca 10.1, Cu 44.3, Cl 16.9, O 24.2, H 1.91, total 97.41.…”