(This July 4 story has been refiled to specify data on gallium is for primary gallium only in paragraph 12 and add Canadian gallium producer in paragraph 8)

(Reuters) - China said on Monday it will impose export restrictions from Aug. 1 on some gallium and germanium products, metals used in computer chips and other products, to protect national security interests.

Here are some facts about gallium and germanium:

WHERE IS GERMANIUM FOUND?

Germanium ores are rare and most germanium is a by-product of zinc production and from coal fly ash.

China produces around 60% of the world's germanium, according to European industry association Critical Raw Materials Alliance (CRMA), with the rest coming from Canada, Finland, Russia and the United States.

China exported 43.7 metric tons of unwrought and wrought germanium last year, according to Chinese customs.

Roughly $39 million worth of germanium was consumed last year, up 10% from 2021, according to the U.S. Geological Survey (USGS).

WHAT ABOUT GALLIUM?

Gallium is found in trace amounts in zinc ores and in bauxite, and gallium metal is produced when processing bauxite to make aluminium. Around 80% is produced in China, according to the CRMA.

Gallium is used to make gallium arsenide for use in electronics. Only a few companies - one in Europe and the rest in Japan and China - can make it at the required purity, says the CRMA. Canadian company Neo Performance Materials said it also makes gallium at the required purity.

China exported 94 metric tons of gallium in 2022, up 25% on the prior year, according to Chinese customs.

U.S. imports of gallium metal and gallium arsenide (GaAs) wafers in 2022 were worth about $3 million and $200 million, respectively, according to USGS.

According to USGS, high-purity refined gallium production last year was estimated at about 290,000 kgs, a 16% increase from 250,000 kgs in 2021.

WHO ELSE PRODUCES THESE METALS?

Small amounts of primary gallium - around 10 metric tons in 2021 - are produced by Japan, Russia and South Korea, according to USGS, while additional amounts also come from recycled material.

Germany and Kazakhstan also produced it in the past. After prices rallied in 2020 and 2021, Germany announced that it would restart primary gallium production.

Canada's Teck Resources is the biggest germanium producer in North America, extracting the material from its Trail smelter in British Columbia.

U.S.-based Indium Corporation also produces germanium, while Belgium's Umicore makes both germanium and gallium.

WHAT ARE THEY USED FOR?

The metals are used in high-speed computer chips and in the defence and renewable energy sectors.