Pyrochlore

Pyrochlore
Pyrochlore from Russia
General
CategoryOxide mineral
Formula
(repeating unit)
(Na,Ca)2Nb2O6(OH,F)
IMA symbolPcl[1]
Strunz classification4.DH.15
Dana classification08.02.01.01
Pyrochlore group
Crystal systemIsometric
Crystal classHexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space groupFd3m (No. 227)
Unit cella = 10.41(6) Å, Z = 8
Identification
ColorBlack to brown, chocolate-brown, reddish brown, amber-orange, red-orange
Crystal habitTypically octahedra, disseminated granular, massive
Twinning111 rare
Cleavage111 indistinct, may be a parting.
FractureSubconchoidal to uneven, splintery
TenacityBrittle
Mohs scale hardness5.0–5.5
LusterVitreous to resinous
StreakWhite
DiaphaneitySubtranslucent to opaque
Specific gravity4.45 to 4.90
Optical propertiesIsotropic, weak anomalous anisotropism
Refractive indexn = 1.9–2.2
Other characteristics Radioactive, often metamict
References[2][3][4][5]

Pyrochlore (Na,Ca)2Nb2O6(OH,F) 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 on ignition in classic blowpipe analysis.[4]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ "Pyrochlor". www.mineralienatlas.de.
  3. ^ "pyrochlore at RRuff database" (PDF). rruff.info. Retrieved 2015-02-03.
  4. ^ a b "Pyrochlore Group: Pyrochlore Group mineral information and data". mindat.org. Retrieved 2015-02-03.
  5. ^ Barthelmy, Dave. "Pyrochlore Mineral Data". webmineral.com. Retrieved 2015-02-03.