Question: are there different types of ounces?
Answer: Besides the common ounce, several other ounces are in current use: The troy ounce of 31.1034768 grams is used for the mass of precious metals such as gold, silver, platinum, palladium, rhodium, etc. The ounce-force is a measure of weight, that is, force. The fluid ounce is a measure of volume.