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Formula: Pb7V5+(O8.5◻0.5)Cl2
Lead oxychloride (oxychorides have both oxygen and chlorine atoms attached to lead atoms in a single molecule; other
components may also be present), vanadium-bearing mineral
Crystal System: Triclinic
Specific gravity: 8.160 calculated for the empirical formula
Hardness: 2½
Streak: Orange
Colour: Orange-red
Environments
Volcanic igneous environments
Metamorphic environments
Janchevite is a relatively new mineral, approved in 2017 and to date reported only from the type locality.
Localities
At the type locality, the Kombat Mine, Kombat, Otavi Constituency, Otjozondjupa Region, Namibia, it is suggested that
janchevite formed as a consequence of regional metamorphism of a
primary lead-,
manganese-, arsenic- and
barium- rich, chemically heterogeneous, volcanic hydrothermal assemblage.
Janchevite was discovered in manganese oxide ore, associated with
baryte, hausmannite,
calcite, magnesite and
kombatite. Janchevite forms thick tabular anhedral to subhedral
grains up to 0.4 x 0.8 x 0.8 mm3 in size in a polymineralic granular aggregate of associated minerals.
Grains of janchevite are translucent and orange-red with an orange streak and adamantine lustre
(CM 56.159-165).
Janchevite from the Kombat Mine - Image
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