Grant Hardy discusses the Nephite monetary system in Alma 11; notes that, although since 1841 some have assumed that "pieces" refers to coins, the text itself is discussing a system of weights and measurements.
Grant Hardy, The Annotated Book of Mormon (Oxford: Oxford University Press, 2023), 341
4. The monetary system in the verses that follow is described as being unique to the Nephites and arising by trial and error out of their particular experience, before being codified by King Mosiah. As early as 1841, an index inserted into copies of the BoM, influenced by the word pieces, referred to these monetary units as “coins,” a term that persisted in LDS editions until 2013. The text itself, however, refers to a system of equivalent weights and measures that corrected precious metals with grain.