Minute quantities of orickite and coyoteite occur with rare alkali iron sulphides in a mafic alkalic diatreme near Orick, Humboldt County. Orickite, NaxKyCu0.95Fe1.06zH2O (x,y < 0.03, z < 0.5), is hexagonal, a 3.695, c 6.16 A, D 4.212 g/cm3, Z = 4. The strongest XRD reflections are 3.08(100), 3.20(90), 2.84(60), 1.73(55), 1.583(30) A. The mineral is brass yellow, opaque, weakly pleochroic, but strongly anisotropic (greyish brown to greyish blue) in reflected light. Orickite is compositionally near to Fe-rich chalcopyrite, but it may be related to synthetic chalcogenides with a distorted wurtzite-(2H) structure. Coyoteite, NaFe3S5.2H2O, is triclinic, P1 or P1, a 7.409(8), b 9.881(6), c 6.441(3) A, alpha 100o25(3)', beta 104o37(5)', gamma 81o29(5)', D 2.879 g/cm3, Z = 2; strongest XRD reflections are 5.12(100), 7.13(90), 3.028(80), 3.080(70), 9.6(60), 5.60(60) A. Coyoteite is black, opaque, weakly pleochroic (pale brownish grey) and strongly anisotropic (grey to dull golden orange) in reflected light. It is unstable under normal atmospheric conditions. -J.A.Z.
Additional publication details
Orickite and coyoteite, two new sulfide minerals from Coyote Peak, Humboldt County, California.