A herdsman in China's remote far west has struck gold after stumbling upon a huge nugget of the precious metal estimated to be worth at least $250,000, state media reported Thursday.

The 7.85 kilo chunk was discovered "practically lying on bare ground", the official Xinhua news agency said, quoting the herder, an ethnic Kazakh named Berek Sawut.

He found the golden lump, described in the report as "random-shaped" and about 23 centimetres long, 18 centimetres at its widest and up to eight centimetres thick.

It was estimated to be worth 1.6 million yuan ($255,000), Xinhua said, assuming it was 80 percent pure.

It quoted a local gold price expert, Zhu Xinfeng, as saying that natural lumps of the precious metal can fetch several times more than the refined variety.

But the report did not say whether the herder would be able to keep his new-found riches.

The discovery was made in the far western region of Xinjiang, a vast and diverse area bordering Central Asia and abundant in natural resources and striking scenery, with an ethnically diverse population including the Kazakhs, Uighurs and Han, China's majority.

The nugget was found in Qinghe county, part of Altay prefecture, the report said, adding that Altay means gold in Mongolian.