Coronadite
| coronadite | |
|---|---|
Coronadita | |
| General | |
| Category | hydroxides |
| Formula | Pb(Mn4+6Mn3+2)O16 |
| IMA symbol | Cor |
| Strunz classification | 4/D.08-70 |
| Dana classification | 7.9.1.4 |
| Crystal system | monoclinic |
| Space group | I2/m |
| Unit cell | a = 9.938, b = 2.8678, c = 9.834, Z = 1; β = 90.39° V = 280.26 |
| Identification | |
| Formula mass | 933.55 |
| Colour | dark grey to black |
| Crystal habit | botryoidal; fibrous |
| Mohs scale hardness | 4.5–5 |
| Luster | submetallic |
| Streak | brownish black |
| Diaphaneity | opaque |
| Density | 5.44 |
| Refractive index | 2.72? |
| Pleochroism | brown-grey |
| Common impurities | Fe, Al |
Coronadite is the lead endmember of the coronadite 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. It is chemically related to ferricoronadite, an Fe+3 analogue, as well as cryptomelane, hollandite, manjiroite and strontiomelane.
- Polyhedral representation of the 2 × 2 tunnel structure of coronadite. The black atoms represent Pb.
