pentagrammin

Pentagrammin is a fictional mineral described in speculative geology and worldbuilding contexts. It is characterized by a pentagonal motif in its crystal and fracture patterns, which has given the mineral its name. In many in-world sources, pentagrammin is presented as a dense, phosphorus-rich metal-bearing mineral with a distinctive star-like appearance when viewed in polished sections.

Composition and structure in these accounts vary, but pentagrammin is typically described as containing phosphorus alongside transition metals such as manganese and iron, with trace amounts of titanium and rare-earth elements. The crystal structure is often portrayed as quasi-crystalline or featuring fivefold symmetry, a feature linked to non-periodic tiling rather than conventional crystal lattices. This structural peculiarity is cited as the source of its star-shaped inclusions and unusual diffraction patterns.

Occurrence and formation are described as occurring in specialized hydrothermal or metamorphic environments. In fictional geologies, pentagrammin is said to form under particular pressure–temperature conditions, sometimes in subduction-zone analogues or other tectonic settings created for worldbuilding purposes. Its deposits are depicted as rare and highly localized, contributing to its status as a coveted and enigmatic material in the imagined world.

Physical properties commonly attributed to pentagrammin include a metallic to submetallic luster, a color range from dark violet to steel gray, a Mohs hardness around 6–7, and a density of about 5.5 g/cm3. Some depictions note faint blue fluorescence under ultraviolet light and a variable magnetic response depending on trace metal content.

In practice, pentagrammin serves as a narrative device in fiction and speculative essays, illustrating how unusual crystal symmetry and dense, star-shaped microstructures might influence material properties in imagined settings. See also: quasicrystals, mineral morphology, and worldbuilding minerals.