Ortidan

Ortidan is a fictional mineral introduced in geology education and speculative mineralogy to illustrate crystallographic and mineral-chemical concepts. It is not part of official mineral nomenclature and does not occur in known natural catalogs.

In typical teaching descriptions, Ortidan is modeled as a silicate mineral with a framework structure comparable to tectosilicates. It is assigned to the orthorhombic crystal system and described as having a vitreous luster, a pale gray to blue color, and a Mohs hardness around 6. Descriptions may include features such as lamellar twinning and stacking faults to demonstrate real-world crystal defects.

Formation and occurrence in these scenarios are fictional as well, often arising from metasomatic or metamorphic processes under high temperature and low fluid activity, with speculative associations to quartz and mica. A notional Ortidan Basin is sometimes used to anchor examples of geological context and mineral associations.

Etymology and use. The name derives from a fictional Ortid region or researcher, and Ortidan is used in textbooks to discuss concepts such as crystal symmetry, polytypism, and the interpretation of limited mineral data. The construct helps learners compare real minerals and understand uncertainty in mineral identification.