Pehmemalt

Pehmemalt is a hypothetical mineral described in theoretical discussions of mineralogy and in speculative fiction. It is portrayed as a hydrous aluminosilicate with a layered silicate framework and a distinctive iridescent sheen when exposed to light, particularly in the ultraviolet range.

The term pehmemalt is a constructed name used in fictional and thought-experimental contexts. There is no widely accepted etymology or formal nomenclature in real geological literature, and the concept varies across different imagined scenarios.

Proposed properties of pehmemalt are variable across descriptions, but it is often depicted as an aluminosilicate with water of hydration. Some renderings give a general formula in terms of oxides and water, while others describe an approximate composition without fixed stoichiometry. Reported physical properties commonly include a Mohs hardness around 5–6, a relatively high refractive index, and strong basal cleavage. The mineral is sometimes said to be thermodynamically stable at moderately high pressures and low to moderate temperatures, with dehydration and phase changes occurring upon heating to several hundred degrees Celsius.

Occurrence and formation narratives place pehmemalt in metamorphic rocks formed under metasomatic hydration in high-pressure, low-temperature regimes, or as a product of hydrothermal processes in tectonically active regions. It is often described as occurring alongside other hydrous minerals.

As a non-existent mineral, pehmemalt has no known natural occurrence or commercial use. It is primarily used in educational hypotheticals and narrative settings to illustrate concepts such as mineral hydration, phase stability, and the influence of microstructure on optical properties.