| Baddeleyite | |
|---|---|
 Baddeleyite in corundum gneiss |
|
| General | |
| Category | Oxide mineral |
| Chemical formula | ZrO2 |
| Strunz classification | 04.DE.35 |
| Dana classification | 04.04.14.01 |
| Identification | |
| Color | Colorless to yellow, green, greenish or reddish brown, brown, iron-black |
| Crystal habit | Tabular prismatic, radially fibrous in botryoidal masses |
| Crystal system | Monoclinic - prismatic |
| 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 |
| 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 |
| Other characteristics | Blue-green cathodoluminescence |
| References | [1][2][3] |
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 (nα = 2.130, nβ = 2.190, and nγ = 2.200), and ranges from colorless to yellow, green, and dark brown. The mineral has a specific gravity of 5.5 to 6 and a Mohs hardness of 6.5. Baddeleyite is a refractory mineral, with a melting point of 2 700 °C. Hafnium is a substituting impurity and may be present in quantities ranging from 0.1 to several percents.
Baddeleyite was first described in 1892 from Sri Lanka, and Minas Gerais and Jacupiranga, São Paulo, Brazil. It was named after Joseph Baddeley, who described the occurrences in Sri Lanka.[1]
Baddeleyete is often found as detrital grains in gravels. Its primary occurrence is in high temperature veins and in syenite, carbonatite, kimberlite, and lamproite intrusions. Because of their refractory nature and stability under diverse conditions, baddeleyete grains, along with zircon, are used for uranium-lead radiometric age determinations.
See also
References
- ^ a b http://rruff.geo.arizona.edu/doclib/hom/baddeleyite.pdf Handbook of Mineralogy
- ^ http://www.webmineral.com/data/Baddeleyite.shtml Webmineral data
- ^ http://www.mindat.org/min-480.html Mindat
- Minweb with chime structure
- Bill Cordura, University of Wisconsin
- Early rocks to reveal their ages, BBC News
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