an·a·tase 
(ănə-tās′, -tāz′)
(ănə-tās′, -tāz′)n.
A rare blue or light yellow to brown crystalline mineral, the rarest of three forms of titanium dioxide, TiO2, used as a pigment, especially in paint.
[French, from Greek anatasis, extension (from its long crystals), from anateinein, anata-, to extend : ana-, ana- + teinein, to stretch; see ten- in the Appendix of Indo-European roots.]