Nordstrandit z kamenolomu Mokrá u Žlutic (Česká republika)

Publication Type:Journal Article
Year of Publication:2015
Authors:Svejkovský, J, Pauliš, P, Malíková, R
Journal:Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze
Volume:23
Issue:1
Start Page:30
Pagination:4
ISSN:1804-6495
Keywords:Czech Republic, Mokrá near Žlutice, nordstrandite, powder X-ray diffraction data, unit-cell parameters
Abstract:

The active quarry Mokrá near Žlutice is a very interesting locality, where the first macroscopic samples of Al hydroxides in volcanic rocks in the Czech Republic were found. Besides previously identified böhmite and gibbsite, a macroscopic aggregates of nordstrandite were found. Nordstrandite occurs there in several generations and forms. It mostly creates yellowish to brownish hemispherical aggregates up to 8 mm with surface formed by thin tabular crystals. In smaller cavities, the mineral occurs in the form of groups of small straw-yellow and translucent tabular crystals forming fan- or hedgehog-like irregular aggregates with a size up to 5 mm. A different form of nordstrandite is represented by a light beige to white compact mass with conchoidal fracture and dull lustre similar to opal. The unit-cell parameters of nordstrandite, refined from powder X-ray data, are: a 5.10(2), b 5.07(2), c 5.12(2) Å, α 70.5(3), β 73.8(3), γ 58.2(3)° and V 2061(5) Å3.

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