Burgessit, nový minerál pro jáchymovský rudní revír (Česká republika)

Publication Type:Journal Article
Year of Publication:2014
Authors:Sejkora, J, Macek, I
Journal:Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze
Volume:22
Issue:2
Start Page:1
Pagination:6
ISSN:1804-6495
Keywords:burgessite, chemical composition, Czech Republic, powder X-ray diffraction data, the Jáchymov ore district, unit-cell parameters
Abstract:

Very rare mineral specie, burgessite Co2(H2O)4[AsO3(OH)]2(H2O), was identified at single historical sample from the Jáchymov ore district, Krušné hory Mountains, Czech Republic. Burgessite occurs as light to purplish red hemisperical aggregates up to 0.8 mm in size formed by elongated prismatic crystals (length to 0.4 mm and diameter of about 10 - 30 μm only). Tiny green thin tabular zeunerite crystals and purple red crusts of amorphous Co-Ni-Cu hydrogen-arsenate phase were found in the association. Burgessite is monoclinic, space group P21/n, the unit-cell parameters refined from the X-ray powder diffraction data are: a 4.672(1), b 9.281(2), c 12.606(3) Å, β 99.11(2)° and V 539.8(2) Å3. The average chemical composition (mean of 8 point analyses) of burgessite CaO 0.10, FeO 0.29, MgO 0.14, CuO 1.51, CoO 16.03, NiO 13.32, ZnO 0.63, As2O5 47.63, P2O5 0.21, SO3 0.72, H2Ocalc. 22.96, total 103.54 wt. % corresponds to the empirical formula (Co1.00Ni0.84Cu0.09Zn0.04Mg0.02Fe0.02Ca0.01)Σ2.02(AsO3OH)1.94(SO4)0.04(PO3OH)0.01·5H2O on the basis of (As+S+P) = 2 apfu. The occurrence of Ni-rich burgessite at the Jáchymov ore district is the second locality of this mineral phase worldwide.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith