| Baddeleyite | |
|---|---|
 Baddeleyite from Phalaborwa, South Africa | |
| General | |
| Category | Oxide mineral |
| Formula (repeating unit) | Zirconium dioxide (ZrO2) |
| IMA symbol | Bdy[1] |
| Strunz classification | 4.DE.35 |
| Dana classification | 04.04.14.01 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/c |
| Unit cell | a = 5.1505 Å, b = 5.2116 Å, c = 5.3173 Å, β = 99.23°; Z = 4 |
| Identification | |
| Color | Colorless to yellow, blue, green, greenish or reddish brown, brown, iron-black |
| Crystal habit | Tabular prismatic, radially fibrous in botryoidal masses |
| Twinning | Ubiquitous polysynthetic on {100} and {110} |
| Cleavage | {001} distinct |
| Fracture | Irregular uneven to subconchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 6.5 |
| Luster | Greasy to vitreous |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 5.5–6 |
| Optical properties | Biaxial (–) |
| Refractive index | nα = 2.130 nβ = 2.190 nγ = 2.200 |
| Birefringence | δ = 0.070 |
| Pleochroism | X = yellow, reddish brown, oil-green; Y = oil-green, reddish brown; Z = brown, light brown |
| 2V angle | Measured: 30° to 31° |
| Dispersion | r > v, rather strong |
| Other characteristics | Blue-green cathodoluminescence |
| References | [2][3][4] |
Baddeleyite is a rare zirconium oxide mineral (ZrO2 or zirconia), occurring in a variety of monoclinic prismatic crystal forms. It is transparent to translucent, has high indices of refraction, and ranges from colorless to yellow, green, and dark brown. See etymology below.
Baddeleyite is a refractory mineral, with a melting point of 2700 °C. Hafnium is a substituting impurity and may be present in quantities ranging from 0.1 to several percent.
It can be found in igneous rocks containing potassium feldspar and plagioclase. Baddeleyite is commonly not found with zircon (ZrSiO4), because it forms in silica-undersaturated rocks, such as mafic rocks. This is because, when silica is free in the system (silica-saturated/oversaturated), zircon is the dominating phase, not baddeleyite. It belongs to the monoclinic-prismatic class, of the P21/c crystal system. It has been used for geochronology.[5]
- ^ 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.
- ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1990). "Baddeleyite". Handbook of Mineralogy (PDF). Vol. III (Halides, Hydroxides, Oxides). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209724. Retrieved December 5, 2011.
- ^ Baddeleyite. Webmineral
- ^ Baddeleyite. Mindat
- ^ Bayanova, T.B. (2006). "Baddeleyite: A promising geochronometer for alkaline and basic magmatism". Petrology. 14 (2): 187–200. Bibcode:2006Petro..14..187B. doi:10.1134/S0869591106020032. S2CID 129079168.