Zektzerite, LiNa(Zr,Ti,Hf)Si6O15, is a new mineral species occuring as colorless to pink euhedral crystals in a riebeckite granite from Okanogan County, Washington. It is orthorhombic, Cmca or C2ca, with a = 14.306(5), b = 17.330(4), c = 10.140(3)A, Z : 8. The strongest reflections (in A) in the X-ray powder pattern are 7.190 78 200; 4.850 100 221; 4.336 78 040; 3.480 75 241; 3.145 85 023,421; and 2.665 65 043,441. Physical properties include perfect cleavages on {100} and {010}, white streak, vitreous luster, Mohs hardness about 6, and density of 2.79 g/cm3. Optically, zektzerite is biaxial negative, almost isotropic, with 2Vx = ∼0°. Indices are α = 1.582(3), β = 1.584(3), and γ = 1.584(3) with orientation X = a, Y = b, and Z = c. Dispersion is very weak, r > υ. Zektzerite is closely related to tuhualite,

(Na,K)2Fe22+Fe23+Si12O30.H2O
⁠, and more distantly to the osumilite group.

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