segulmagns

Segulmagns is a rare sulfide mineral in the manganese-magnesium-sulfur system. It forms primarily from hydrothermal fluids rich in manganese and magnesium and is typically found in metamorphosed mafic to ultramafic rocks. The idealized composition is reported as a manganese-magnesium sulfide with minor iron and nickel substituting for manganese. The mineral is named for the Segul region, where the first specimens were located.

Segulmagns crystallizes in the monoclinic system and often occurs as tabular to prismatic crystals, up to several millimeters in length. It has a metallic to submetallic luster, a steel-gray to bronze color, and a dark gray streak. Hardness is in the range of 4 to 5 on the Mohs scale; density measurements fall around 4.9–5.1 g/cm3. Cleavage is imperfect along the {010} and {001} planes, and fracture is uneven. The mineral commonly tarnishes to iridescent colors when exposed to air.

Segulmagns is typically associated with sulfide-rich veins within foliated metamorphic rocks and with hydrothermal breccias in intrusion-related settings. It commonly occurs together with other Mn-rich minerals such as spessartine and manganite, as well as magnesium-rich sulfides.

It was first described in 2010 by field geologists working in the Segul Basin. The name segulmagns reflects the type locality and the dominant Mn and Mg composition. Since its initial description, additional occurrences have been reported in several other regions with similar hydrothermal histories.

Because segulmagns contains manganese, it has attracted some interest as a minor ore of Mn and Mg in specialized deposits, though it is not a major source compared to other Mn minerals. It is primarily of interest to mineralogists and collectors, and is used in research on sulfide solid solution and metamorphic mineral paragenesis.