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Introduction The mineral specimens had been collected by Blair Gartrell. He noticed a number of minerals that he could not identified. This led to the discovery of two new minerals, Ashbutonite named after the place, and gartrellite named after him [3]. Ashburtonite approved IMA in 1989. Composition The chemical formula of Ashburtonite is HPb4Cu4Si4O12(HCO3)4(OH)4Cl [3]. The percentage was calculated to be found as: Grice performed the chemical analysis on a JEOL superprobe using Tracon Northern 600 automation. The operating voltage was 15 kV, and the beam current was 0.02 µm. To minimize the decomposition of the sample under the electron beam, three spectrometers were used simultaneously. No elements were indicated by a 100 energy dispersive with Z>9 except those which are reported her were present. Cubrite (Cu Kα), mimetite (Cl Kα), sanbornite (Si Kα), and crocoites (Pb Mα) used as standards. Infrared spectroscopy and crystal structure analysis established the presence of CO -23 and OH- ions corresponding to Pb3.99Cu4.01HSi4.00O12.03(HCO3)4.00(OH)4.00Cl1.10. Geological Occurrence In a weathered shear zone that cuts a series of shales and graywackers. However, it presents as substitute to galena and chalcopytite. These secondary minerals composed of hydrated carbonates, arsenates, and sulfates of Pb and Cu, and to a much lesser extent of Zn and Fe.[3]. The occurrence of Ashburtonite linked with beudantite, brochantite, according to Nickel, calerdonite, cerussite, diaboleite, duftite, malachite, platterite, adamite, antlerite, bayldonite, bindheimite, carminite, chenevixite, chlorargyrite, chrysocolla, cinnabar, hemimorphite, hydrozincite, jarosite, lavendulan, linarite, mimatite, olivenite, paratacamite, and rosasite. Atomic Structure The crystal system is tetragonal dipyrimal. And the H-M symbol is 4/m, with a space group of I4/m. Although there are other possible space groups we will talk about it later. The unit cell dimension are a=14.235, c=6.103; Z=2, V=1236 [3] Cromer and Mann (1968) and Cromer and Liberman (1970) solved the Ashburtonite structure using derict methods with SHELXTL PC package of programs [3]. There were other possible space groups such as I4 and I4*. Hamilton (1965), by using all the intensity data and the weighting sheme prescribed, refined them. Using Hamilton’s (1965) R-ratio test, which find the Rg for each space group I4/m=2.61, I4=2.51, and I4*=2.45, gives I4* a slight preference among the three space groups. But the dipyramidal morphology indicates 4/m point group. And that proves that the space group of Ashburtonite is I4/m. The figure shows four membered Si tetrahedral rings and Cu as octahedra. Pb atoms are the dark balls, Cl white ball, CO3 groups are shaded triangles with plane approximately parallel to (100) [3]. The X-ray powder diffraction pattern for Ashburtonite is 10.2 (100), 4.495 (100), 3.333 (100), 3.013 (90), 5.644 (70), 2.611 (50), 2.805 (30) (Mineral Data Publishing, 2001) Ashburtonite has a blue color with a light blue streak. It is a transparent mineral and it has a vitreous luster. The fracture is very brittle, which produces small fragments without cleavage. The hardness hasn’t been accurately determined, because it of its small size grain that makes it difficult to test. Ashburtonite is uniaxial (+) w=1.786, e=1.8 [3]. The mineral photographed in figure 4, and its physical and optical properties are summarized in table 2. Special Characteristics Ashburtonite has small fragments that make determining its hardness difficult. And only few minerals described as Bicarbonates. Ashburtonite only found in Anticline prospects 11.2 km southwest of Ashburton Downs in Western Australia. References 1. ^ http://webmineral.com/data/Ashburtonite.shtml Webmineral
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