THE MINERAL SAFFLORITE

Chemistry: (Co, Fe)As₂, Cobalt Iron Arsenide.
Class: Sulfides
Subclass: Arsenides
Group: Marcasite and Lollingite
Uses: As a very minor ore of cobalt and arsenic and as mineral specimens.
Specimens

Safflorite is a rare mineral, but is found with other arsenides and thus it is included with them when mined for cobalt and/or arsenic. When weathered it is associated with the pink to red cobalt arsenate mineral erythrite. This is good because safflorite lacks other good distinguishing characteristics, especially from the closely related lollingite and other arsenic sulfides. Lollingite has more iron than cobalt in its chemistry. Another closely related mineral is rammelsbergite, which has more nickel than cobalt. These minerals represent the three most common members of the Lollingite Group. This group is sometimes placed in the larger Marcasite Group.

Safflorite is a near dimorph with the mineral clinosafflorite. A dimorph is a set of two minerals that share the same chemistry but have different structures. In this case clinosafflorite's formula is (Co, Fe, Ni)As₂. Not quite an exact dimorph with the addition of the nickel, but safflorite often contains traces of nickel, just not as much. Clinosafflorite gets its name by virtue of its monoclinic symmetry compared to safflorite's orthorhombic symmetry (inclined safflorite, in other words). Twinning is common in safflorite and forms star shaped trillings. Cobalt minerals are sometimes interesting to collect and safflorite is certainly interesting.

PHYSICAL CHARACTERISTICS:

Color is tin white (darkens upon exposure to air).
Luster is metallic.
Transparency: Crystals are opaque.
Crystal System is orthorhombic; 2/m 2/m 2/m
Crystal Habits include tiny tabular to prismatic crystals and fibrous masses (sometimes radially fibrous). Also compact and massive. Twins are seen as star shaped trillings.
Cleavage is indistinct.
Fracture: Conchoidal.
Hardness is 4.5 - 5
Specific Gravity is approximately 6.9 - 7.4 (well above average for metallic minerals)
Streak is a black.
Associated Minerals include arsenic, cobaltite, arsenopyrite, skutterudite, calcite and erythrite.
Notable Occurrences include Schneeburg, Harz Mountains, Germany; Great Bear Lake, Ontario, Canada; Lafayette County, Wisconsin and Oregon, USA; Javornik, Czech Republic and the type locality of Nordmark, Varmland, Sweden.
Best Field Indicators are crystal habits, color (dark tarnish), associations, streak, hardness and density.