Okanoganite is found in miarolitic cavities in the arfvedsonite granite phase of the Golden Horn batholith, near Washington Pass, Okanogan County, Washington. It occurs as tan to pale pink pseudotetrahedral twinned crystals up to 4 mm across. A combination of electron microprobe analyses and spectrophotometric analyses for B2O3 give the following formula: (Na6.40Ca2.40Pb0.20)[(Y,Ce,Nd,La)31.92Ca1.78Fe1.61](Si17.29Ti0.46)B6.44O81.00F42.48, with an ideal formula of (Na,Ca)3(Y,Ce,Nd,La)12Si6B2O27F14. The crystals are pseudotetrahedral fourlings with twin plane {0114}, the c face of each individual forming the faces of the pseudotetrahedron. The mineral is rhombohedral with possible space group R3, R3, R32, R3m, R3m, R3c, or R3c. The cell dimensions are a = 10.72(1), c = 27.05(8)Å, Z = 3 (hexagonal cell) or a = 10.94(3)Å, α = 58.7(3)°, Z = 1 (rhombohedral cell). D(meas) = 4.35, D(calc) = 4.37. The strongest lines [d, (I), (hkl)] of the X-ray powder pattern (68 given) are 4.38(41)(202); 3.11(48)(300); 2.970(100)(027); 2.939(95)(125); 2.926(50)(303); 2.676(32)(220); 1.978(35)(325,413); 1.822(32)(3.0.12); 1.784(43)(330,2.0.14). The refractive indices are ω = 1.753, ε = 1.740; the mineral shows no dichroism and is colorless in thin fragments; streak = white; H = 4. It shows no fluorescence or phosphorescence under UV radiation and does not cathodeluminesce. The name is for Okanogan County, Washington.

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