METHOD OF REFINING NATURAL MINERALS Russian patent published in 1997 - IPC

FIELD: jewelry. SUBSTANCE: invention relates to methods of treating natural minerals in order to improve their jewelry properties, in particular, charoites. Polished samples of charoite rock of various modifications are degreased with acetone or alcohol and dyed with 3-10% aqueous solution of active organic dye (active brilliantly violet 4KF, mixture of active red 6F and active turquoise K) with neutral electrolyte additive at 90 C for three days. Active dyes contain functional groups capable to form strong covalent bonds with samples. Dyes penetrate to a depth from 0.5 mm to full dyeing depending on structure and mineral constitution of samples. Acquired coloration is resistant to atmosphere conditions, water, soda, weak alkalis, acids, and temperatures up to 200 C. Dyeing does not fade in the sun and allows to preserve texture peculiarities of charoite. Treated samples of low-grade cheap charoite acquire intense violet color which confers them high jewelry quality. EFFECT: upgraded low-grade minerals. 3 cl, 1 tbl