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Formula: Cu3SbSe3
Sulphosalt, copper-, antimony- and
selenium- bearing mineral
Crystal System: Orthorhombic
Specific gravity: 6.324 calculated for the empirical formula
Hardness: 2 to 3
Colour: Steel-grey
Environments
Bytizite is a relatively new mineral, approved in 2016.
Localities
The type locality is the Mine dump, Uranium Mine No. 16, Háje, Příbram District, Central Bohemian Region, Czech
Republic. In this ore district, there are four main mineralisation stages:
(1) siderite–sulphides
(2) calcite
(3) calcite–uraninite
(4) calcite-sulphides
Selenide mineralisation occurs in close association with
uraninite of the
calcite–uraninite mineralisation,
but selenides are always younger than
uraninite. It is uncertain whether the
selenides at Príbram formed at the end of the
calcite–uraninite stage, or at
the beginning of the following calcite–sulphides stage.
The first selenide found there was
clausthalite, reported in 1986; subsequently, eight more
selenides were found in 2004. Since 2005, many more specimens of a
selenide-containing gangue have been
found in the dump material. This material contains a very rich selenide
assemblage, including bytízite.
The selenium-uranium
mineralisation is of low-temperature hydrothermal origin and is confined to
calcite veins with a thickness varying from tens of centimetres to several
metres. The main ore is represented by uraninite, while younger
pyrobitumen predominates in deeper parts of the deposit. Macroscopically, bytízite forms a substantial part of
up to 1 mm large steel-grey grains in a calcite vein several millimetres
thick. This younger carbonate vein cuts perpendicularly through an older
calcite vein containing common
umangite and uraninite, so
umangite is unequivocally older than other
selenides in the association. Bytízite forms anhedral grains
enclosing other coexisting selenides such as
chaméanite, bukovite,
príbramite, eskebornite,
crookesite and
giraudite-(Zn).
Therefore, bytízite appears to be the youngest selenide in the
association. Hakite and
tetrahedrite also occur, probably as relatively late phases.
Bytízite forms anhedral grains 10 to 40 µm across, growing together in aggregates up to 300 µm across. The
mineral is steel-grey in colour and opaque with a metallic lustre. No cleavage or fracture were observed.
(MM 82.1.199–209).
Bytízite from Příbram - Image
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