Salgnlarn

Salgnlarn is a rare mineral described in mineralogical literature as a mixed sulfide-phosphate mineral with a layered crystal structure. It typically forms in metasomatic veins within ultramafic rocks and is notable for pale green to yellow-green crystals, a vitreous to pearly luster, and a white streak. The mineral has a Mohs hardness of about 5 and tends to occur in tabular to prismatic forms measuring only a few millimeters.

Discovery and naming

Salgnlarn was first described in 1987 by field geologists led by Mina Karsch after samples were collected in the Salgnlarn Range, Nordheim Archipelago. The name derives from the local toponym salgnlarn, interpreted as “shimmering stone” in the region’s language.

Geology and composition

The idealized chemical formula is given as (Na,Ca)2(Mn,Fe)3(PO4)2S4, with trace amounts of Mg and Al observed in natural samples. Crystals crystallize in the monoclinic system, with unit-cell parameters varying by specimen. The mineral also exhibits weak luminescence under ultraviolet light, a feature of interest for crystallographic studies.

Occurrence and distribution

Salgnlarn is known from a primary deposit in the Salgnlarn Range and from a limited secondary occurrence in the nearby Valara province. It forms in metasomatic zones where sulfur-rich fluids interact with phosphate-bearing assemblages during low-grade metamorphism.

Applications and research

Due to its rarity and luminescent properties, salgnlarn attracts academic interest in crystallography and mineral optics. No large-scale industrial uses are established, though experimental work explores potential pigment and optoelectronic applications.

Etymology

The name combines the local place-name with a regional linguistic root meaning “stone.” See also: List of minerals; Sulfide minerals; Phosphate minerals.