Bulletin Mineralogie Petrologie

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) ų

Bosmans H. J. (1970) Unit cell and crystal structure od nordstrandite, Al(OH)₃. Acta crystallogr., Sect. B, 26, 649-652.

Černý P., Černý P., Habermann V., Koloušek D., Ondruš P., Veselovský F. (2002) Mokrá u Žlutic, lokalita gibbsitu, böhmitu a zeolitů. Minerál 10, 6, 403-408.

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Sejkora J., Jebavá I., Plášil J., Bureš B., Tvrdý J. (2010) Nordstrandit z lomu v Děpoltovicích u Karlových Varů (Česká republika). Bull. mineral.- petrolog.Odd. Nár. Muz. (Praha) 18/1, 33-41.

Svejkovský J., Dvořák Z. (2002) Gibbsit z kamenolomu Mokrá u Žlutic. Bull.mineral.- petrolog. Odd. Nár. Muz. (Praha) 10, 333 - 334.

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