Imperial and US customary measurement systems different concepts – the imperial gallon is defined in terms of the volume occupied by a specified mass of water, while the US gallon is specified in terms of cubic linear measure. Notes Notes Units of weight in both the imperial and US customary system always used the same standard, though differences in multiples of the avoirdupois pound developed in the nineteenth century. Both systems used the three different scales – the avoirdupois system for general use, the troy system for precious metals and the apothecaries system in the pharmacy industry. The term "weight" and "mass" are used interchangeably in
Texas Precious Metals Metals (NASDAQ: AMRK), a publicly traded precious metals wholesaler, to manufacture and distribute Texas Mint products to dealers throughout the United States. In 2014, Texas Precious Metals and the Perth Mint of Australia released the Houston-Perth "Sister Cities" coin, commemorating the strong ties between the cities' energy sectors. The half-ounce, 99.9% pure silver coin features offshore and onshore oil rigs showcasing the cities' historic energy sectors. The coin also pays homage to the flags of Texas and Australia. The coin measures 32mm in diameter with a thickness of 2mm, and has a legal tender face value of AUD$0.50. The coins