Formula: Ni6Fe2(SO4)(OH)16.4H2O Hexagonal
Description: Honessite is one of a number of secondary nickel sulphates formed by the weathering of primary hydrothermal nickel sulfides such as millerite, violarite or nickeliferous pyrite ( so-called “Bravoite”). It is found at several localities in southwestern Wisconsin’s zinc-lead district, where it was studied intensively by Heyl and others (1959b). The material referred to as honessite was a poorly crystallized mixture of microscopically fibrous earthy orange-red, yellow or green minerals. Their refractive indices were about 1.615. They exhibited low birefringence, positive elongation and a maximum extinction angle of 12 degrees. Microchemical analysis showed significant cobalt and calcium in the material, as well as iron and nickel. In the absence of detailed x-ray analysis, it seems best to use the name honessite as a general term for this complex mixture.
IOWA COUNTY: Honessite was found in small amounts at the several mines in T.5N. R.2E. near Linden. These include the Glanville Mine (SW SW Sec. 8) ; the Mason Mine (SE SW Sec. 8) T.5N R.2E and the Gilman Mine (SW SE Sec. 16). Honessite was also found at the Dodgeville #2 Mine in the north half of NW Sec. 34 T.6N R.3E (Heyl et al., 1959b).
LAFAYETTE COUNTY: Honessite is found at the Farrey Mine, near Lead Mine in the NE NW Sec. 14, T.1N R.1E. It is also reported from the James mine, near Shullsburg in the SW Sec. 9 T.1N R.2E (Heyl et al., 1959b).
MILWAUKEE COUNTY: A pale green coating on long millerite fibers found in geodes along the Milwaukee River at Estabrook Park (Sec. 5 T.7N R.22E) may be in part honessite (Bagrowski, 1940).