Last minted 1970. Half crown Cupro-nickel, silver appearance Two shillings and sixpence. Half mark or merke Out of use in mediaeval times. One third of a pound, six shillings and eightpence. Third guinea Gold, or alloyed gold.
Older coins have much more than their face value in gold content.
Weight of 1804 George III example 2.72g. Half sovereign Gold, or alloyed gold. Older coins have much more than their face value in gold content. George V example 4g. Obviously ten shillings, or 50 new pence.