CHAROITE with AEGIRINE MINIATURE

Charoite is a rare silicate mineral characterized by the chemical formula K(Ca,Na)2Si4O10(OH,F)•H2O, first identified in 1978. Its name is derived from the Chara River, located 70 kilometers from where it was discovered. Initially, the mineral was suspected to be a synthetic creation due to its vibrant purple hue, which led to misconceptions about its authenticity.

Charoite exhibits a translucent lavender to purple coloration and possesses a pearly luster. It is primarily found in a massive form with conchoidal fractures and features a unique swirling, fibrous texture that can appear chatoyant. Although it was reportedly discovered in the 1940s, it gained wider recognition only after its formal description in 1978. In its natural state, charoite may appear opaque and unremarkable, which likely contributed to its delayed acknowledgment. The mineral's composition includes significant amounts of oxygen (43.75%), silicon (27.65%), and calcium (17.53%), along with potassium (10.69%) that imparts radioactive properties, and a small amount of hydrogen (0.39%). Its radioactivity is minimal, with a concentration of 0.65% per Gamma Ray American Petroleum Institute Units.

Aegirine belongs to the clinopyroxene group of inosilicate minerals and serves as the sodium endmember of the aegirine–augite series. Its chemical composition is represented by the formula NaFeSi2O6, where iron exists as the Fe3+ ion. Within the aegirine–augite series, sodium can be partially substituted by calcium, while iron(II) and magnesium can replace iron(III) to maintain charge balance. Additionally, aluminum can substitute for iron(III). A notable variety of this mineral is acmite, which is characterized by its fibrous green appearance.

Aegirine typically forms dark green monoclinic prismatic crystals, exhibiting a glassy luster and perfect cleavage. Its hardness on the Mohs scale ranges from 5 to 6, and it has a specific gravity that falls between 3.2 and 3.4.