zirkelite

{{Infobox mineral | name = Zirkelite | boxwidth = | boxbgcolor = | image = | imagesize = | alt = | caption = | category = Oxide mineral | formula = {{chem2|(Ti,Ca,Zr)O_{(2-x)}|}} | IMAsymbol = Zke | molweight = | strunz = 4.DL.05 | dana = | system = Isometric | class = Hexoctahedral (mm) H-M symbol: (4/m 2/m) | unit cell = a = 5.02 Å, Z = 4 | color = Black, reddish brown | habit = Crystalline, metamict, pseudocubic | twinning = | cleavage = None | fracture = Brittle | tenacity = | mohs = | luster = Resinous | streak = Brownish grey | diaphaneity = Subtranslucent to opaque | gravity = | density = 4.7 | polish = | opticalprop = | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = 25px Radioactive | prop1 = | prop1text = | references = | var1 = | var1text = | var2 = | var2text = | var3 = | var3text = | var4 = | var4text = | var5 = | var5text = | var6 = | var6text = }} Zirkelite is an oxide mineral with the chemical formula . It occurs as well-formed fine sized isometric crystals. It is a black, brown or yellow mineral with a hardness of 5.5 and a specific gravity of 4.7.

==Name and discovery== Zirkelite was first discovered in Brazil in 1895. It was named for German petrographer Ferdinand Zirkel (1838–1912).