What is a microgram?
A microgram is one millionth of a gram, written μg. Doses of some vitamins and medicines are measured in micrograms, and a grain of table salt weighs roughly 60μg.
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.