Mark (unit) Mark (unit) The Mark (from Middle High German: Marc, march, brand) is originally a medieval weight or mass unit, which supplanted the pound weight as a precious metals and coinage weight from the 11th century. The Mark is traditionally a half pound weight and was usually divided into 8 ounces or 16 Lot. The significance of the "Cologne Mark" (Kölner Mark) in the German-speaking areas corresponded to about 234 gram. Like the German systems, the French poids de marc weight system considered one "Marc" equal to half-a-pound (8 ounces). Like the pound of 12 troy ounces (373 g), the mark
Refractory metals to other refractory metals, where it adds ductility and tensile strength. Rhenium alloys are being used in electronic components, gyroscopes and nuclear reactors. Rhenium finds its most important use as a catalyst. It is used as a catalyst in reactions such as alkylation, dealkylation, hydrogenation and oxidation. However its rarity makes it the most expensive of the refractory metals. Refractory metals and alloys attract the attention of investigators because of their remarkable properties and promising practical usefulness. Physical properties of refractory metals, such as molybdenum, tantalum and tungsten, their strength, and high-temperature stability make them suitable material for hot metalworking