Assertion: titanium | /r/PartOf | about 0.57%
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Source sentences:
text: Titanium is relatively common in the Earth's crust, making up about 0.57% (the 9th most common element), but extracting it from its ores -- the minerals Rutile (TiO 2 ), Ilmenite (FeTiO 3 ) and Sphene (CaTiSiO 5 ) -- can be pricey, due to the high heat input required.