Zimbabwe's gold miner RioZim on Tuesday said it would take legal action to force the central bank to pay it in US dollars for part of its output, signalling impatience by mining companies over acute dollar shortages afflicting the economy. The shortages have worsened since 2016 and are the biggest concern for foreign investors seeking a foothold in Zimbabwe, which is trying to recover after 20 years of economic hardship under former leader Robert Mugabe.