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A daring holdup at the California museum for mining that boasts the largest nugget from the gold rush era netted an estimated $2 million in gold and gems.

The two armed bandits did not make off with the 201-ounce prized possession of the California State Mining and Mineral Museum, but the Friday heist took in several fist-sized nuggets, according to the California Highway Patrol, which is leading the investigation. The thieves walked into the museum, located in Mariposa, and threatened staffers before taking the booty, Park Superintendent Greg Martin said to the Merced Sun-Star.

It was not immediately known exactly how much of the precious stones and minerals were lifted, but museum officials believe it was at least $2 million worth. The sheer size of some of the gold nuggets could make it difficult for the thieves to sell on the black market, officials said.

“It may be difficult to sell the kind of items that may have been taken, as it is uncommon for most citizens to possess such minerals,” read a bulletin released by the CHP.

No suspects have been identified as investigators are still pursuing leads.

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“It’s kind of like a hit-and-run accident. There’s bits of info that point us in the possible direction, but the investigation is still open as we try to find the suspects,” Officer Tim Kilenease told FoxNews.com.

A complete inspection of the museum’s inventory will be made later this week to determine what and how much was taken during the stickup, a spokesperson for the California State Parks Department told the newspaper.

In addition to the 201-ounce gold nugget, the museum also houses a large sample of the state gem benitoite and collections of silver ore and California jade, as well as artifacts from the state’s mining era, according to the Sun-Star.

The museum’s collection was originally housed in San Francisco beginning in 1881 before being moved to Mariposa in 1983. The state Department of Parks and Recreation took over management of the collection in 1991.

The museum was actually facing closure this past summer when state park funding was reduced, but it was put on hold indefinitely after $54 million in unaccounted state funds was discovered.