Sundialid

Sundialid is a fictional mineral species used in speculative geology and science fiction to illustrate principles of crystallography and timekeeping. The term combines "sundial" with the -id suffix common to mineral names, signaling a pattern-based, time-oriented mineral form. In narrative and thought experiments, sundialid crystals are described as forming in hexagonal to prismatic habits with distinct concentric growth rings visible on the crystal faces, reminiscent of a sundial's hour lines.

Physical properties in fictional treatments often list a vitreous to resinous luster, an approximate Mohs hardness around 5–6, and a pale to emerald-blue to amber color range. The mineral is said to exhibit pronounced zonation, with concentric spectral bands that align with solar exposure during growth. Some accounts describe faint luminescence under ultraviolet light, producing visible lines that can be interpreted as solar "hour marks."

Occurrence is described as laboratory-synthesized or simulated in hydrothermal experiments rather than as a naturally occurring mineral. In stories, sundialid serves as an educational example of how light-driven processes can influence crystal growth and as a plot device in timekeeping or chronometry technology.

Because sundialid is not a real mineral, it is not listed in official mineral databases and has no established taxonomy beyond fictional usage. The concept remains popular in educational and speculative contexts for illustrating pattern formation and the relationship between light and crystallization.