Coyoteite

Abstract: Orickite and coyoteite occur with rare alkali iron sulfides in a mafic alkalic diatreme near Orick, Humboldt County, California. Both minerals are very rare, and only a few milligrams of each have been found. Orickite, Na,KrCuse5Fer.ooSz.zHzO (x,y < 0.03, z < 0.5), is hexagonal; a:3.695, c : 6.164 (both t0.0lA); D = 4.212 g cm-3 forZ:4. The six strongest lines in the X-ray diffraction powder pattern are [d in A, t, (*ttt):3.08, 100, (002); 3.20 90, (100); 2.84,60, (l0l); 1.73,55, (103); 1.583,30, (ll2);2.20, 15, (102). The mineral is brass yellow and opaque, weakly pleochroic, but strongly anisotropic (from grayish brown to grayish blue) in reflected light. Orickite is compositionally near iron-rich chalcopyrite, but the mineral may be related to synthetic chalcogenides having a distorted wurtzite-\2[I) structure. Coyoteite, NaFe3S5.2H2O, is triclinic, Pl or Pl; a : 7.409(8), b : 9.881(6), c =