U.S. gold futures hit a six-month high of $1,000 and spot gold also rose to six-month high on Tuesday as the dollar's weakness, concerns about the sustainability of global economic recovery and worries about future inflation underpinned sentiment.
Gold for December delivery touched $1,000, shortly after spot gold hit a six-month high above $997.20.
The following are key dates in gold's trading history since the early 1970s:
* August 1971 - United States President Richard Nixon takes the dollar off the 'gold standard', which fixed paper notes value to a pre-set quantity of gold. It had been in place, with minor modifications, since the Bretton Woods Agreement of 1944 fixed the conversion rate for one Troy ounce of gold at $35.
* August 1972 - U.S. devalues dollar to $38 per ounce of gold.
* March 1973 - Most major countries adopt floating exchange rate system.
* May - U.S. devalues dollar to $42.22 per ounce.
* January 1980 - Gold hits record high at $850 per ounce. High inflation because of strong oil prices, Soviet intervention in Afghanistan and the impact of the Iranian revolution, prompts investors to move into the metal.
* August 1999 - Gold falls to a low at $251.70 on worries about central banks reducing reserves of gold bullion and mining companies selling gold in forward markets to protect against falling prices.
* October 1999 - Gold reaches a two-year high at $338 after agreement to limit gold sales by 15 European central banks. Market sentiment toward gold begins to turn more positive.
* February 2003 - Gold reaches a 4- year high on safe-haven buying in run-up to conflict with Iraq.
* December-January 2004 - Gold breaks above $400, reaching levels last traded in 1988. Investors increasingly buy gold as risk insurance for portfolios.
* November 2005 - Spot gold breaches $500 for the first time since December 1987, when spot hit $502.97.
* April 11, 2006 - Gold prices surpass $600, the highest point since December 1980, with funds and investors pouring money into commodities on a weak dollar, firm oil prices and geopolitical worries.
* May 12 - Gold prices peak at $730 an ounce with funds and investors pouring money into commodities on a weak dollar, firm oil prices and political tensions over Iran's nuclear ambitions.
* June 14 - Gold falls 26 percent to $543 from its 26-year peak after investors and speculators sell out of commodity positions.
* November 7, 2007 - Spot gold hits a 28-year high of $845.40 an ounce.
* January 2, 2008 - Spot gold breaks above $850.
* March 13 - Benchmark gold contract trades over $1,000 for the first time in U.S. futures market.
* March 17 - Spot gold hits an all-time high of $1,030.80 an ounce. U.S. gold futures touch record peak of $1,033.90.
* Sept 17 - Spot gold rises by nearly $90 an ounce, a record one-day gain, as investors seek safety amid turmoil on the equity markets.
* Feb 20, 2009 - U.S. gold futures rise back above $1,000 an ounce to a peak of $1,005.40 as investors turn to gold as major economies face recession and equity markets tumble.
* Sept 8 - U.S. gold futures hit $1,000 an ounce for the first time since February as the dollar's weakness, concerns about the sustainability of global economic recovery and worries about future inflation underpinned sentiment.
Sources: Reuters, GFMS Ltd, World Gold Council, Commodity Research Bureau
(Reporting by Miho Yoshikawa, Compiled by Jan Harvey; Editing by Gillian Murdoch and Ben Tan)