BERYL MAXIXE and " MAXIXE-TYPE". These are jewelry varieties of beryl of a thick blue color. The color is caused by defects in the crystal lattice of beryl; natural radioactive irradiation, the entry of boron atoms into the structure of beryl, a large number of alkalis (especially caesium). Maxixe beryl was first described in 1917. It got its name from the place of discovery of this variety-the Maxixe mine in Brazil (Minas Gerais state).
It has a post-magmatic origin, was found in lithium-cesium granite pegmatite. Maxixe beryl forms elongated prismatic crystals, crystallizes in a hexagonal syngony. Its accompanying minerals are quartz, microcline, spodumene, albite, muscovite, topaz, sherl, magnetite, hematite. The color of maxixe beryl is dark blue, indigo-blue, cornflower blue. The color is unstable. Under the influence of ultraviolet light and even just daylight or when heated above 100°C, beryl quickly loses its rich blue color, becoming almost transparent, with a slight bluish tint. Due to the unstable color, this type of beryl has not found application in jewelry, but serves as a collector's mineral.
In 1970, new cobalt-blue beryls appeared on the market, which were very expensive. In addition to the unusual color, they also had unusual optical properties - these stones had a deeper color belonging to an ordinary ray (for example, aquamarine — unusual), which made it possible to use the color of the stone in the most advantageous way when cutting, placing the pad perpendicular to the optical axis. These beryls in their properties resembled blue beryls-maxixe - they also noticeably faded in the sun. The stones were carefully examined by K. Nassau, who found that when irradiated with neutrons or other sources of penetrating radiation, the color of such stones was restored. After that, any dark blue beryls that have the optical properties of "maxixe" beryl were proposed to be called "maxixe-type" beryls.
