Vishnevye Mts (Vishnyovye; Cherry), Chelyabinsk Oblast', Southern Urals, Urals Region, Russia

Item-No.: MIN2580
Price: 185.00 EUR 

Synonyms:  Azor-phyrrite, Azorpyrrhite, Endeiolite, Fluochlor, Hydrochlor, Niobpyrochlor, Pyrochlor
IMA status:  Not recognized, name for a group of niobium dominant members of Pyrochlore Supergroup
Classification:  Oxides, Pyrochlor Group
Chemical formula:  A2Nb2(O,OH)6Z   {A = Na, Ca, Sn2+, Sr, Pb2+, Sb3+, Y, U4+, H2O ; Z = OH, F, O, H2O}
Crystal system:  Isometric
Density (g/cm3):  4,2 - 6,4 calculated
Tenacity:  splintery
Cleavage:  Indistinct on {111}
Fracture:  Irregular/uneven, splintery, sub-conchoidal
Hardness (Mohs):  5 - 5,5
Colour:  Brown, yellowish-brown, yellow, greenisch-brown, reddisch-brown, black
Lustre:  Vitreous, Resinous
Streak:  Yellowish-brown
Transparency:  Transparent to opaque
Type locality:  Stavern (Fredriksvärn), Larvik, Vestfold, Norway
Application:  Source of niobium, tantalum and thorium