Jan 26 (Thomson Reuters Foundation) – An attractive alternative investment or no better than a Ponzi scheme? Cryptocurrencies are controversial – challenging conventional financial wisdom and worrying regulatory authorities around the world. But few recent launches of virtual currencies have provoked as much debate as the maricoin, which its founders billed as the world’s first LGBT+ cryptocurrency and rolled out for a pilot test in Madrid on Dec. 31. Even its name, a play on words drawn from a homophobic insult in Spanish, has proved controversial. With the maricoin set to start trading on major exchanges on Feb. 22, what are cryptocurrencies and just why has this particular debut made waves? Why are cryptocurrencies contentious? In contrast to traditional currencies, cryptocurrencies are not issued by any central bank or government and are operated privately. The best-known, bitcoin, was first traded in 2009, with its value jumping from just under 10 U.S. cents then to more than $34,000 today. Critics of digital currencies point to their volatility and say their use could undermine authorities’ control of global financial and monetary systems, increase systemic risk, fuel white-collar crime and hurt investors.