Recently, a collector decided to open two physical Casascius bitcoin bars, each containing 100 BTC, with a total value of approximately $19.2 million.
Entrepreneur Mike Caldwell created the Casascius line, issuing not only coins of various denominations but also hefty bars calibrated to 100 BTC, 500 BTC, and 1000 BTC. For example, in series 1 (S1), Caldwell released 57 bars of 100 BTC, and only seven of them remained untouched.
Coins with denominations of 1, 10, 25, 100, and 1000 BTC were also issued.
Diameter is 1.125 inches
Solid brass
Year indicated on the coins: 2011
Approximately 0.24 ounces
Eight-digit 'primordials' are inkjet printed on the surface of the holographic sticker
First appeared in September 2011
Private key: a string of 22 characters inside the coin, a 256-bit private key encoded using the SHA256 system (string)
Approximate number of coins produced: 3500 as of November 2011
