'Flammable ice

China claims breakthrough in mining 'flammable ice'

Chinese authorities have described the success as a major breakthrough.

Methane hydrates, also called "flammable ice", hold vast reserves of natural gas.

Many countries including the US and Japan are working on how to tap those reserves, but mining and extracting are extremely difficult.

What is 'flammable ice'?

The catchy phrase describes a frozen mixture of water and gas.