Troy weight in the context of "Osmium"

Silver is a chemical element; it has symbol Ag (from Latin argentum 'silver') and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. Silver is found in the Earth's crust in the pure, free elemental form ("native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining.

Silver has long been valued as a precious metal, commonly sold and marketed beside gold and platinum. Silver metal is used in many bullion coins, sometimes alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. In terms of scarcity, silver is the most abundant of the big three precious metals—platinum, gold, and silver—among these, platinum is the rarest with around 139 troy ounces of silver mined for every one ounce of platinum.

The mask of Tutankhamun is a gold funerary mask that belonged to Tutankhamun, who reigned over the New Kingdom of Egypt from 1332 BC to 1323 BC, during the Eighteenth Dynasty. After being buried with Tutankhamun's mummy for over 3,000 years, it was found in 1925 following the discovery of Tutankhamun's tomb three years earlier by the British archaeologist Howard Carter at the Valley of the Kings. It is on public display at the Grand Egyptian Museum in Cairo.

Bearing the likeness of Tutankhamun in the form of Osiris, the Egyptian god of the afterlife, the mask is 54 centimetres (21.3 in) tall, weighs over 10 kilograms (22 lb) or 321.5 troy ounces, and is decorated with semi-precious stones. A spell from the Book of the Dead is inscribed in Egyptian hieroglyphs on its shoulders. In 2015, it was restored after its 2.5-kilogram (5.5 lb) plaited beard fell off and was hastily glued back on by museum workers.

A grain is a unit of measurement of mass, and in the troy weight, avoirdupois, and apothecaries' systems, equal to exactly 64.79891 milligrams. It is nominally based upon the mass of a single ideal seed of a cereal. From the Bronze Age into the Renaissance, the average masses of wheat and barley grains were part of the legal definitions of units of mass. Expressions such as "thirty-two grains of wheat, taken from the middle of the ear" appear to have been ritualistic formulas. Another source states that it was defined such that 252.458 units would balance 1 cubic inch (16 cm) of distilled water at an ambient air-water pressure and temperature of 30 inches of mercury (100 kPa) and 62 °F (17 °C) respectively. Another book states that Captain Henry Kater, of the British Standards Commission, arrived at this value experimentally.

The grain was the legal foundation of traditional English weight systems, and is the only unit that is equal throughout the troy, avoirdupois, and apothecaries' systems of mass. The unit was based on the weight of a single grain of barley which was equal to about +4⁄3 the weight of a single grain of wheat. The fundamental unit of the pre-1527 English weight system, known as Tower weights, was based on the wheat grain. The tower "wheat" grain was defined as exactly +45⁄64 (≈+3⁄4) of the troy "barley" grain.

A pennyweight (dwt) is a unit of mass equal to 24 grains, 1⁄20 of a troy ounce, 1⁄240 of a troy pound, 48⁄875 avoirdupois ounce and exactly 1.55517384 grams. It is abbreviated dwt, d standing for denarius – (an ancient Roman coin), and later used as the symbol of an old British penny (see £sd).

The apothecaries' system, or apothecaries' weights and measures, is a historical system of mass and volume units that were used by physicians and apothecaries for medical prescriptions, and also sometimes by scientists. The English version of the system is closely related to the English troy system of weights, the pound and grain being exactly the same in both. It divides a pound into 12 ounces, an ounce into 8 drachms, and a drachm into 3 scruples of 20 grains each. This exact form of the system was used in the United Kingdom; in some of its former colonies, it survived well into the 20th century. The apothecaries' system of measures is a similar system of volume units based on the fluid ounce. For a long time, medical recipes were written in Latin, often using special symbols to denote weights and measures.

The use of different measure and weight systems depending on the purpose was an almost universal phenomenon in Europe between the decline of the Roman Empire and metrication. This was connected with international commerce, especially with the need to use the standards of the target market and to compensate for a common weighing practice that caused a difference between actual and nominal weight. In the 19th century, most European countries or cities still had at least a "commercial" or "civil" system (such as the English avoirdupois system) for general trading, and a second system (such as the troy system) for precious metals such as gold and silver. The system for precious metals was usually divided in a different way from the commercial system, often using special units such as the carat. More significantly, it was often based on different weight standards.

A zolotnik (Russian: золотни́к, abbr.: zol.) is an obsolete Russian unit of weight, equal to 0.1505 avoirdupois ounces, 0.13715 troy ounce, or 4.2658 grams (about 65.83 grains). Used from the 10th to 20th centuries, its name is derived from the Russian word zoloto, meaning gold. As a unit, the zolotnik was the standard for silver manufacture, much as the troy ounce is currently used for gold and other precious metals.

This unit was originally based on a coin of the same name. The zolotnik circulated in the Kievan Rus until the 11th century; it was equal in weight to the Byzantine Empire's solidus.