What are Troy Ounces?
A troy ounce is the unit gold, silver and platinum prices are quoted in. It is about 10% heavier than an avoirdupois ounce, but a troy pound has only 12 of them.
One troy ounce is equivalent to approximately 31.1035 grams, which is about 10% heavier than a standard avoirdupois ounce. The term "troy" originates from the city of Troyes in France, where this unit of measurement was historically used in the trade of precious metals.
What is a long hundredweight?
A long hundredweight, also known as the imperial hundredweight, is the hundredweight of the United Kingdom and, despite the name, is not 100 pounds. The 100 pound version is the short hundredweight used in the United States.
It is equivalent to 112 pounds or approximately 50.802 kilograms. The long hundredweight is often used in trade and commerce for measuring bulk goods such as grains, coal, and other commodities.
To get metric tons, multiply long hundredweights by 0.0508, since one is about 50.802 kilograms and a metric ton is 1,000 – 5 long hundredweights is about 0.254 metric tons. Dividing by 20 gives long tons instead, because 20 hundredweights make a long ton.