scrutinyite

{{Infobox mineral | name = Scrutinyite | category = Oxide mineral | boxwidth = | boxbgcolor = | image = Scrutinyite.jpg | imagesize = | caption = | formula = PbO2 | IMAsymbol = Sny | molweight = 239.20 g/mol | system = Orthorhombic | class = Dipyramidal (mmm) H–M Symbol: (2/m 2/m 2/m) | symmetry = Pbcn | unit cell = a = 4.91 Å, b = 5.95 Å c = 5.43 Å; Z = 4 | strunz = 4.DB.20 | color = Dark reddish brown | habit = Crystalline, platy | twinning = | cleavage = {100} perfect, {010} imperfect | fracture = Brittle | mohs = | luster = Sub-metallic | refractive = n > 2 | opticalprop = Biaxial | birefringence = | pleochroism = | streak = Dark brown | gravity = 9.867 (calculated) | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent to translucent | other = Non-fluorescent, nonmagnetic | references = }} Scrutinyite is a rare oxide mineral and is the alpha crystalline form of lead dioxide (α-PbO2), plattnerite being the other, beta form. The mineral was first reported in 1988 and its name reflects the scrutiny and efforts required to identify it from a very limited amount of available sample material.

==Identification== The synthetic orthorhombic form of lead dioxide, α-PbO2, was known from 1941. Although natural lead dioxide has been known, as the mineral plattnerite (β-PbO2), since 1845, its alpha form could only be recognized in 1981 and reliably identified in 1988.