Pyrochlore
Chemical compound
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Pyrochlore (Na, Ca)₂Nb₂O₆ is a mineral group of the niobium end member of the pyrochlore supergroup. Pyrochlore is also a term for the crystal structure Fd3m. The name is from the Greek πῦρ, fire, and χλωρός, green because it typically turns green... Wikipedia
Crystal system: Isometric
Cleavage: 111 indistinct, may be a parting
Color: Black to brown, chocolate-brown, reddish brown, amber-orange, red-orange
Crystal class: Hexoctahedral (m3m); H-M symbol: (4/m 3 2/m)
Crystal habit: Typically octahedra, disseminated granular, massive
Dana classification: 08.02.01.01; Pyrochlore group
Formula (repeating unit): (Na,Ca)2Nb2O6(OH,F)