Coronadite

coronadite
Coronadita
General
Categoryhydroxides
Formula
(repeating unit)		Pb(Mn4+6Mn3+2)O16
IMA symbolCor[1]
Strunz classification4/D.08-70
Dana classification7.9.1.4
Crystal systemmonoclinic
Space groupI2/m
Unit cella = 9.938, b = 2.8678, c = 9.834, Z = 1; β = 90.39° V = 280.26
Identification
Formula mass933.55
Colourdark grey to black
Crystal habitbotryoidal; fibrous
Mohs scale hardness4.5–5
Lustersubmetallic
Streakbrownish black
Diaphaneityopaque
Density5.44
Refractive index2.72?
Pleochroismbrown-grey
Common impuritiesFe, Al

Coronadite is the lead endmember of the hollandite group, a family of tectomanganates with a 2 × 2 tunnel structure. The mineral was named after Francisco Vasquez de Coronado who was an explorer of southwest US. The name was made up by Waldemar Lindgren in 1905.[2]

  • Polyhedral representation of the 2 × 2 tunnel structure of coronadite. The black atoms represent Pb.
    Polyhedral representation of the 2 × 2 tunnel structure of coronadite. The black atoms represent Pb.

References

  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. ^ "Coronadite Mineral Data". webmineral.com.