Shum is a unit of gold in the Nephite reckoning. The reckoning included “a senine of gold, a seon of gold, a shum of gold, and a limnah of gold” (Alma 11:5).
A shum of gold “was twice the value of a seon” (Alma 11:9).
In the text
Alma 11:5 — Listed third in the gold reckoning summary
Alma 11:9 — Defined as a gold piece worth twice a seon
