Zirkelite

{{Infobox mineral

| name = Zirkelite

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| category = Oxide mineral

| formula = {{chem2|(Ti,Ca,Zr)O_{(2-x)}|}}

| IMAsymbol = Zke{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

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| strunz = 4.DL.05

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| system = Isometric

| class = Hexoctahedral (m{{overline|3}}m)
H-M symbol: (4/m {{overline|3}} 2/m)

| unit cell = a = 5.02 Å, Z = 4

| color = Black, reddish brown

| habit = Crystalline, metamict, pseudocubic

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| cleavage = None

| fracture = Brittle

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| luster = Resinous

| streak = Brownish grey

| diaphaneity = Subtranslucent to opaque{{Cite web|url=http://www.webmineral.com/data/Zirkelite.shtml#.VfLMJygViko|title = Zirkelite Mineral Data}}

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| density = 4.7

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| other = 25px Radioactive

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Zirkelite is an oxide mineral with the chemical formula {{chem2|(Ca,Th,Ce)Zr(Ti,Nb)2O7}}. 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.