Gold was diving 9.5%, reaching at its lowest level since February 2011 on Monday, and equities related to the metal were feeling the wrath of traders.

A downturn was in effect throughout the commodities complex, but gold was suffering through a two-session stretch unlike anything it's seen in three decades. On the day, it was falling $143 an ounce to $1,358.40. Silver was also slumping, shedding 11.8% to $23.23 an ounce.

Gold, five-day chart. Source: FactSet

For the shares of the miners themselves, the selloff was astonishing -- 52-week lows, or worse, were not uncommon. The sector's stocks were much weaker than the market overall, which was down in its own right.

Barrick Gold (ABX), one of the biggest members of the group, was giving back 10.5% to $20.24. At one point, it was under $20, a price it hasn't broken since October 2008 when the market was falling apart amid the financial crisis. It was also necessary to return to those days to find a session in which Barrick plunged further.

Using FactSet data that go back to 1985, Barrick has only had 17 single days in which it surrendered 10% or more. Monday was one of them.

Freeport-McMoRan (FCX), another large miner, was falling 7.6% to $29.49, while Newmont Mining (NEM) was losing 5.7% to $34.30.

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Elsewhere, AngloGold Ashanti (AU) was sliding 7.8% to $18.82, and Goldcorp (GG) was down 5.4% to $28.07. Kinross Gold (KGC) was dropping 11.3% to $5.61. Randgold Resources (GOLD) was off 6.6% at $70.29 -- basically, if a company had anything to do with gold, it was down, and down hard.

Widely held precious metals ETFs were taking a similar beating. The SPDR Gold Shares (GLD) was off 8% to $132.33, a percentage decline that, if it holds, would be the worst session ever for the exchange-traded fund. The iShares Silver Trust (SLV) was declining 9.8% to $22.81.

Gold prices started the year around $1,676 an ounce. Factoring in the last two days, it's lost around 18% in 2013.