A physical unit of Bitcoin that comes in the form of brass, silver or gold-plated coins.
A Casascius coin is a physical Bitcoin unit that comes in various designs, sizes and types, typically owned by niche collectors.
Invented by Mike Caldwell in 2011, Casascius coins are some of the first known-examples of so-called “physical bitcoins” — that is, BTC stored within a physical structure, such as a coin or bar. Mike Caldwell continued producing Casascius coins until 2013, but shut down the operation due to the intervention of the Financial Crimes Enforcement Network (FINCEN) who believed the activity may be considered money transmitting, and hence require a license.
Over the course of his three-year project, Mike minted and added value to a total of 27,938 Casascius coins and bars with an estimated worth of 91,262.8 BTC. Due to their limited number, Casascius coins are considered to be an attractive investment opportunity, and typically command a premium over their “peel value” — that is, the sum total of the cryptocurrency they contain.
Not all Casascius coins contain actual BTC. They can come either loaded or unloaded, with unloaded coins lacking the private key that is usually used to redeem any associated bitcoin.
Since the creation of Casascius coins, a variety of other types of physical Bitcoin have emerged under various names, some of which include: Alitin Mint, Titan Bitcoin, Cryptmint coins, Antana coins, Ravenbit Satoshi coin, CoinedBits and Lealana coins.