feldspatia

Feldspatia is a fictional mineral species in the feldspar group, created for educational and theoretical discussions of crustal minerals. It is used in texts to illustrate alkali feldspar concepts. The composition is described as a solid solution between potassium- and sodium-rich feldspars, with the general formula (K,Na)AlSi3O8 and occasional Ca substituting, yielding varying K/Na ratios.

Occurrence and formation are described in the hypothetical model as late-stage crystallization in granitic magmas and pegmatites, often alongside quartz, muscovite, and other feldspars. Feldspatia can appear as prismatic crystals in granular to massive aggregates, sometimes showing zonation related to cooling rates.

Physical properties include a light color and vitreous luster, Mohs hardness around 6, and a specific gravity near 2.6–2.8. It exhibits two cleavages near 90 degrees and a conchoidal to uneven fracture when broken. Color ranges from colorless to pale pink or gray, with crystals that may be transparent in well-formed specimens. The mineral is typically described as having a medium to high refractive index and strong cleavage plains under standard optical examination.

Identification and uses rely on cleavage, optical properties, and composition. In teaching contexts, Feldspatia helps illustrate solid-solution behavior in feldspars and serves as a basis for discussing dating methods that involve potassium-bearing minerals, as well as the role of feldspars in ceramic and glass technologies.

Relationship to real minerals: Feldspatia is not recognized in current geology and is distinct from actual feldspar varieties such as orthoclase, microcline, and plagioclase. The concept primarily serves as a didactic tool to compare alkali feldspar groups and their behaviors.