The Greek noun gaza (G1047) is a loanword of Persian origin (ganza) meaning treasure, treasury, or royal wealth. It appears in Acts 8:27 describing the Ethiopian eunuch as being in charge of the entire treasury of Candace, queen of the Ethiopians.
The Ethiopian official's charge over the royal gaza — the royal treasury — makes his encounter with Philip all the more striking. Here is a man of great earthly wealth and honor, yet he is reading Isaiah 53, seeking the deeper treasure. His baptism represents the fulfillment of Psalm 68:31 ("Ethiopia shall stretch out her hands to God") and previews the global reach of the Gospel. The greatest treasure one can find is not gold but the knowledge of the Suffering Servant.