The first finding of sassolite (H3BO3) in fluid inclusions in minerals

Daughter crystals of sassolite, crystalline boric acid (H3BO3), have been f irst found in gas-liquid inclusions in minerals from the pegmatite veins Mi ka and Amazonitovaya in the Kukurt gemstone district (Central Pamirs). The crystals at sassolite are rounded, tabular, less frequently, idiomorphic, w ith low refractive indices and high birefringence. The Raman spectrum of sa ssolite has an intense line near 880 cm(-1) and a weaker one at 499 cm(-1) Sassolite crystals in inclusions of types 1 and 2 in quartz from the miarol itic cavity of the Mika vein occur in associations with daughter crystals o f halite and Cs-bearing sylvite. In inclusions of type 3 in quartz and tour maline of the Mika vein and in quartz and adularia of the Amazonitovaya vei n sassolite is the only daughter mineral. Study of sassolite-bearing inclusions has shown that the miarolitic cavitie s and near-cavity complexes of the Mika and Amazonitovaya pegmatite veins c ontain concentrated solutions of boric add (6.7-14.8 and 5.9-10.0 wt. % H3B O3, respectively), chlorides and fluorides of K, Li, Cs, Fe, and Mn, and CO 2. The presence of daughter sassolite suggests of boron migration in the fo rm of H3BO3 under hydrothermal conditions. The data obtained are of great i nterest tar reconstructing the conditions of formation of bath granite pegm atites and hydrothermal systems where baron actively participated in minera l formation.