During the California gold rush, small-denomination coins became hard to find. So beginning in 1852, enterprising parties struck their own privately minted quarters, half dollars and dollar coins from local gold. Such private coinage was made illegal by the Coinage Act of April 22, 1864, but enforcement was limited for nearly 20 years. These coins were often underweight and hard to handle, so their acceptability was limited. But with their unique history and gold content (up to 85% of face value), they quickly became popular among collectors.