A gold brick can refer to several things, depending on the context:

1、Physical Gold Brick (Bullion)
A rectangular block of pure or nearly pure gold, typically produced by mints or refineries、
Common weights:
1 kilogram (32.15 troy oz)
400 troy oz (12.4 kg) – Standard Good Delivery bar (used in central banks)
Smaller sizes (1 oz, 10 oz, 100 g) for private investors、
Used for investment, central bank reserves, or industrial purposes、

2、Scam or Fraud (Fool's Gold)
Historically, swindlers would sell fake gold bricks (lead or other metals coated in gold)、
The phrase selling a gold brick means deceiving someone with a false promise of value、

3、Metaphorical Meaning
Something that appears valuable but is actually worthless or deceptive、
Example: *His investment scheme turned out to be a gold brick.*

4、Pop Culture References
Movies/Books: Often used as a symbol of wealth or heist loot (e.g., *The Italian Job*)、
Games: Found in treasure hunts or as highvalue items (e.g., *Minecraft* gold blocks)、

Would you like details on buying/selling gold bricks, or are you referring to a different context?