Fatto generale: 1870 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1870 is the product of two consecutive Fibonacci numbers.
Trivia: 1870 is an unremarkable number.
Data storica: February 12th is the day in 1851 that Edward Hargraves announces that he has found gold in Bathurst, New South Wales, Australia, starting the Australian gold rush.