Giovanni_Segantini_-_The_Angel_of_Life_-_Google_Art_Project

Mosaic gold or bronze powder refers to

tin(IV) sulfide Tin(IV) sulfide is a compound with the formula . The compound crystallizes in the cadmium iodide motif, with the Sn(IV) situated in "octahedral holes' defined by six sulfide centers. It occurs naturally as the rare mineral berndtite. It is useful ...

as used as a pigment in bronzing and

gilding Gilding is a decorative technique for applying a very thin coating of gold over solid surfaces such as metal (most common), wood, porcelain, or stone. A gilded object is also described as "gilt". Where metal is gilded, the metal below was tradi ...

wood and metal work. It is obtained as a yellow scaly crystalline powder. The

alchemist Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscience, protoscientific tradition that was historically practiced in Chinese alchemy, C ...

s referred to it as aurum musivum, or aurum mosaicum. The term mosaic gold has also been used to refer to

ormolu Ormolu (; from French ''or moulu'', "ground/pounded gold") is the gilding technique of applying finely ground, high-carat gold– mercury amalgam to an object of bronze, and for objects finished in this way. The mercury is driven off in a kiln le ...

and to cut shapes of

gold leaf Gold leaf is gold that has been hammered into thin sheets (usually around 0.1 µm thick) by goldbeating and is often used for gilding. Gold leaf is available in a wide variety of karats and shades. The most commonly used gold is 22-kara ...

, some darkened for contrast, arranged as a

mosaic A mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and were particularly pop ...

. The term bronze powder may also refer to powdered

bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloids such ...

alloy. Mosaic gold appeared in Europe after the 14th century. Alchemists prepared it by combining

mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

sal ammoniac Salammoniac, also sal ammoniac or salmiac, is a rare naturally occurring mineral composed of ammonium chloride, NH4Cl. It forms colorless, white, or yellow-brown crystals in the isometric-hexoctahedral class. It has very poor cleavage and is ...

, and sublimated

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

(fleur de soufre), grinding, mixing, then setting them for three hours in a sand heat. The dirty sublimate being taken off, aurum mosaicum was found at the bottom of the

matrass A matrass (mod. Latin ''matracium'') is a glass vessel with a round or oval body and a long narrow neck, used in chemistry as a digester or distiller. The Florence flask of commerce is frequently used for this purpose. The word is possibly identical ...

. In the past it was used for medical purposes in most chronic and nervous ailments, and particularly

convulsion A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is sometimes used as a s ...

s of children;
/ref> however, it is no longer recommended for any medical uses.

References

{{reflist , 30em Inorganic pigments Visual arts materials Alchemical substances Tin(IV) compounds Powders Sulfides

See also

References