baddeleyite

{{Infobox mineral | name = Baddeleyite | category = Oxide mineral | boxwidth = | boxbgcolor = | image = Baddeleyite-md12a.jpg | imagesize = | alt = | caption = Baddeleyite from Phalaborwa, South Africa | formula = Zirconium dioxide (ZrO2) |IMAsymbol=Bdy | molweight = | strunz = 4.DE.35 | dana = 04.04.14.01 | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = P21/c | unit cell = a = 5.1505 Å, b = 5.2116 Å, c = 5.3173 Å, β = 99.23°; Z = 4 | color = Colorless to yellow, blue, green, greenish or reddish brown, brown, iron-black | colour = | 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 = 6.5 | luster = Greasy to vitreous | streak = White | diaphaneity = Transparent to translucent | gravity = 5.5–6 | density = | polish = | opticalprop = Biaxial (–) | refractive = 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 = Measured: 30° to 31° | dispersion = r > v, rather strong | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = Blue-green cathodoluminescence | alteration = | references = }}

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.