At last, a Tuesday Trivia that is actually being held on Tuesday. Thank goodness for reminders. I'm also trying out a Javascript solution to hide the answers.

1. In what state did the gold rush that began in 1848 take place?
Answer California

2. What is a double denomination error?
Answer A note with one denomination on one side and a different denomination on the other side.

3. When did Australia strike its first commemorative coin?
Answer 1927 (florin)

4. Who was appointed Chief Engraver of the U.S. Mint in 1948, serving until late 1964?
Answer Gilroy Roberts

5. When a design is recessed, rather than raised, it is called intaglio or what?
Answer Incused