Solulimassa

Solulimassa is the proposed name for a luminescent silicate phase observed in ultrahigh-temperature metamorphic rocks. The term blends sol, Latin for sun, and massa, mass, in reference to its bright appearance and dense feel. It was introduced in mineralogical literature in the early 2000s by researchers studying granulite facies rocks in the Alpine belt.

Occurrence and formation: Reports describe solulimassa as small prismatic crystals embedded in garnet-bearing granulites, often as inclusions within garnet or in intergrowths with cordierite. It is believed to form during regional metamorphism when silica-rich fluids interact with iron- and titanium-bearing minerals at high temperatures.

Composition and structure: Solulimassa is described as an aluminosilicate-rich phase with iron and titanium as trace components. Analyses note a dense solid solution between related silicate endmembers. The precise endmember chemistry varies between occurrences, and no fixed empirical formula has been universally adopted.

Physical properties: The mineral is reported to have a Mohs hardness around 6, a density near 3.8–4.0 g/cm3, and a color range from pale brown to golden. It exhibits a warm amber luminescence under ultraviolet light, which has contributed to its name and interest among researchers.

Taxonomy and status: Solulimassa is not universally accepted as a distinct mineral species. Some researchers treat it as a specific textural feature or a subphase within an existing aluminosilicate, requiring more evidence. Ongoing work aims to obtain definitive crystallographic data and a formal chemical description.

Significance: If confirmed, solulimassa could help illuminate high-grade metamorphism processes and provide a luminescence-based dating signal in certain rocks. The term remains largely of theoretical and descriptive value, with potential speculative applications in optical materials discussed but not established.

See also: Luminescent minerals; Aluminosilicates; Metamorphic rocks; Mineral nomenclature.