Gold and platinum prices reached new highs Friday after mine stoppages in South Africa, a leading producer of the precious metals, led to buying on supply concerns.

Several major mining companies, including AngloGold, Harmony and Gold Fields Ltd., suspended all but emergency operations at some of the world’s largest mines because of a national electricity emergency.

An ounce of gold for February delivery spiked to $924.30, a fresh record, on the New York Mercantile Exchange.

April platinum peaked at a new high of $1,694.90 an ounce. Prices later settled at $1,670, up $57.