Murnon

Murnon is a rare mineral described in mineralogical literature as a framework aluminosilicate. The name is derived from the Murn region, where the type locality lies, and follows standard mineral-naming conventions honoring the area and researchers associated with its discovery. The species was first reported in 1994 by a field-based geologist after examination of metamorphic rock samples collected in the region. Because only a small number of specimens are known, many of its properties are inferred from related minerals and remain subject to revision.

Composition and structure of murnon are governed by a three-dimensional aluminosilicate framework built from tetrahedrally coordinated silicon and aluminum. The chemical composition is variable, with idealized formulations often cited as approximately (Al,Fe)2Si4O12, and substitutions by magnesium, calcium, sodium, and potassium occurring in trace amounts. The crystal system is reported as monoclinic, with crystals ranging from prismatic to tabular in habit. Murnon typically presents a pale blue to azure color, a vitreous luster, and a white streak. Its hardness is estimated at about 5 to 6 on the Mohs scale, and it is transparent to translucent in well-formed specimens.

Occurrence and formation of murnon are linked to regional metamorphism in the Murn region, where rocks experience moderate pressure and hydration conditions that favor aluminosilicate formation. It is commonly found in association with quartz, muscovite, garnet, and chlorite. Due to its scarcity, murnon has limited practical use and is primarily of interest for academic study and as a reference point in the classification of framework silicates.

See also: aluminosilicate minerals, metamorphic rocks, phosphate-free framework silicates.