New data on ktenasite

Abstract

SUMMARY. Ktenasite from Glomsrudkollen zinc mine, Modum, Norway, is menoclinic, space group P21/c.The cell dimensions are a 5'598, b 6.121, c 23'762/~, /5 95.55 ~ The chemical formula is (Cu3.sZnl.5)(SO4)~ (OH)n.6H20 with Z = 2; Pcale 2"96 g/cm 3, Pobs 2"94 g/cm 3. The mineral is biaxial negative with ~ (colourless) 1'574,/5 (bluish green) 1'615, v (light green) 1.628, 2V~ 59 ~ KTENASITE was originally described by Kokkoros (195o) from the Kamariza mine, Laurium, Greece, where it occurs sparingly as blue-green, platy crystals up to I mm, in association with smithsonite, glaucocerinite, and serpierite. The symmetry of ktenasite, determined by Weissenberg studies, is monoclinic, space group P21/c. Kokkoros concluded from a partial microchemical analysis on 2"5 mg (Table II) that the mineral is a sulphate of copper and zinc with the formula (Cu,Zn)~SO4(OH)4.2H20; there was, however, poor agreement between the observed and calculated densities.No other well-established occurrence of ktenasite seems to be reported in the literature. Ktenasite is mentioned by Rankin (1969) from the Ecton mine, Montgomery County, Pennsylvania, but no data are given and there must be doubt as to the identification.In I972 a green, platy mineral was detected by amateur collectors on material from the Glomsrudkollen zinc mine, Modum, Norway. It was subsequently identified as ktenasite by Raade, who also noted that Kokkoros's X-ray powder data were obtained on impure material. Some of the Norwegian ktenasite was later sent to Dr. A. Livingstone, Edinburgh, who, because of poor agreement with the published X-ray powder data, asked the British Museum (N.H.) for assistance. A description of this mineral is the subject of the present paper. Specimens are deposited in the British Museum (N.H.), London, the Mineralogical-Geological Museum, University of Oslo, and in the Royal Scottish Museum, Edinburgh.Occurrence. Glomsrudkollen mine is a contact deposit between quartz porphyry and limestone, situated within the Oslo Region (Goldschmidt, 191 I). The dump at the entrance of the lowest adit, now partly removed, was locally rich in sulphides, mainly sphalerite, pyrite, and chalcopyrite. Rock and mineral fragments of the dump were commonly cemented to a sort of breccia by secondary sulphates, mainly gypsum. In some places ktenasite occurred rather abundantly as aggregates of thin platy crystals or laths up to I ram, often growing on, and thus younger than, clear gypsum crystals. A thin coating of a pale blue mineral, shown by microchemical tests to be a Cu-Zn-A1 sulphate, has so far not been identified. Its X-ray powder pattern has broad and diffuse lines; scanning electron micrographs reveal an aggregate of platy crystals.The ktenasite-bearing material appeared when the dumps were taken out for road filling. Temporarily, large amounts of bianchite were seen to have precipitated as a white powder 9

Some observations on the properties of dypingite, Mg5(CO3)4(OH)2·5H2O, and related minerals

“…The disk was prepared using 200 mg KBr for 1 mg of sample. There are many similarities between the spectrum of the present sample and the dypingite of Raade (1970). A significant difference, however, is …”

New data for lansfordite

“…This relatively uniform CO2 loss (about 8 ~ by weight) is broken by a dramatic exothermic peak at 510~ followed immediately by a strong endothermic peak and a sudden weight loss of some 15~. Similar exothermic peaks around 500 ~ have been observed during the decarbonation of nesquehonite (Davies and Bubela, 1973), dypingite (Raade, 1970), and hydromagnesite (Sawada et al, 1979) and are interpreted as representing the crystallization of MgCO 3 from a partially decarbonated amorphous intermediate phase. The rapid evolution of heat accompanying this crystallization decomposes the MgCO 3 almost immediately and gives rise to an endothermic reaction and rapid CO2 loss.…”

Spectroscopy of selected copper group minerals: ktenasite, orthoserpierite and kipushite

“…Subsequently, the mineral was described from Italy and Cornwall by Mellini et al [3]. Olsen and Lewis [6] reported that ktenasite from Creede, Colorado, was richer in zinc than copper [3][4][5][6]. Recently, Ohnishi et al [7] described the first occurrence of ktenasite from Japan and presented EPMA and crystal structure analyses [7].…”

“…Ktenasite forms as the result of the oxidation of copper and zinc sulphide minerals. A green platy mineral from the Glomsrudkollen zinc mine, Modum, Norway, was identified as ktenasite by Raade et al [5], and they proposed the chemical formula (Cu,Zn) 5 (SO 4 ) 2 (OH) 6 Á6H 2 O. Subsequently, the mineral was described from Italy and Cornwall by Mellini et al [3].…”