Mosaic gold, preparation

Stannic sulfide may be prepared as a yellow amorphous precipitate by double decomposition of a stannic salt with hydrogen sulfide. The crystalline modification, known as mosaic gold, may be prepared by sulfurizing stannous sulfide in the following way ... 

Tin(IV) sulfide can be prepared by hydrogen sulfide precipitation of Sn(IV) from solution, to produce a microcrystalline material that is contaminated with oxide. Mosaic gold is a crystalline form of tin(IV) sulfide prepared by high-tempera-ture sublimation procedures. Mosaic gold is the reported product of heating mixtures of (1) tin and sulfur (2) tin, sulfur, and ammonium chloride (3) tin, sulfur, mercury, and ammonium chloride 9 (4) tin(II) oxide, sulfur, and ammonium chloride 9 (5) tin(II) chloride and sulfur 9 (6) tin(II) sulfide, tin(II) chloride, and sulfur.9... 

Stannic sulphide, SnS2, is the higher sulphide of tin, and can be prepared by direct combination of the metal or, still better, of the lower sulphide, SnS, with sulphur. Under ordinary conditions these two substances will not react at a temperature below that which will decompose stannic sulphide. If, however, they are mixed with ammonium chloride the presence of this substance makes possible the combination at a lower temperature. The stannic sulphide formed in this way appears as soft, glistening, yellow crystals. It is used as a bronzing powder, and is known under the name of mosaic gold. In physical properties it is very different from the stannic sulphide which can be precipitated by hydrogen sulphide from a solution of stannic chloride. 

This product, under the name of mosaic gold, is used in the paint industry. As tin-bronze, it is also employed for bronzing. Instructions for preparing products with somewhat brighter or redder color tones are given in the appended original literature. 

Tm(lV) sulfide (berndtite-type or mosaic gold) is a bronze or golden yellow hexagonal crystalline compound (SnS2). It decomposes at 600°C and can be prepared by the reaction of hydrogen sulfide with a soluble tin(lV) salt or by the action of heat on thiostannic acid, H2SnS3. 

Tin(IV) sulphide is prepared commercially as yellow platelets (density 4 51) by the action of tin foil upon flowers of sulphur, and is used as mosaic gold and may be purified by sublimation. It is precipitated from mildly acid solutions of tin(IV) salts by sulphide ion. 

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