This was the first time the term “Black Friday” was used. It was coined by New York Times in response to the financial panic, caused by manipulation of the price of gold. The scheme was carried out by J Fisk and J Gould. They managed to recruit Abel Corbin, president Grant’s brother-in-law, to persuade president to start selling gold, and to gain access to inside information about when are the sellouts going to be. As a result of their activity on September 24th, 1869 the price of gold fell dramatically within minutes when government started selling. People lost fortunes. It had far reaching disrupting consequences for the economy, as gold was the cornerstone of monetary policy in the US at the time. Foreign trade was halted, export of agricultural products fell by over 50%.
The picture below is the photograph of the transaction board in the New York Gold Room on that day. It shows the prices at which the deals were made. The photograph was used in the subsequent congressional investigation, which was substantially limited because the members of the presidential family were not allowed to testify. Needless to say, presidential reputation was damaged by the crisis.

image from http://en.wikipedia.org/wiki/Black_Friday_(1869)

based on:
http://www.nytimes.com/learning/general/onthisday/harp/1016.html
http://en.wikipedia.org/wiki/Black_Friday_(1869)