The Metal Bulletin 62% iron ore fines price dropped 6% or $US3.57 to $55.63 per tonne, its lowest level since April.
MB 58% fines dropped 3.3% or $1.71 to $49.43/t.
The slump came as Port Hedland and Brazil reported rising iron ore exports.
Metals in London were mixed with nickel up nearly 1.5% to $12,157/t.
Tin and zinc were down by around 1% each.
Spot gold was sitting at $1165.90 an ounce or $A1526.30/oz ahead of the Greek referendum on Sunday.
Investec said that while a ‘yes’ vote would bring additional political uncertainty for Greece, it should provide short-term certainty for financial markets.
The Euro Stoxx was down 0.9% overnight.
Wall Street was flat after the release of June payroll figures, released a day early due to the closure of the market on Friday ahead of Independence Day.
While the economy added 233,000 jobs and the unemployment rate dropped to 5.3%, the results missed estimates and slightly lowered the chance of a September interest rate rise.
