At 1505 GMT, the rand traded at 14.4550 against the dollar, 1.3% weaker than its previous close.
Investors were worried about the spread of the Delta variant of COVID-19 around the world, leading some countries to impose tighter curbs while others have extended restrictions.
South Africa, the worst-hit on the African continent in terms of recorded cases and deaths, tightened its restrictions on Sunday.
Investors will look to a U.S. non-farm payrolls report on Friday for clues about the Fed's next move.
Riskier currencies such as the rand thrive on U.S. interest rates remaining low because they benefit from the interest rate differential that increases their appeal for carry trade.
"The foreign exchange markets are likely to remain cautious ahead of the U.S. data tomorrow," analysts at Nedbank said in a note.
Stocks on the Johannesburg Stock Exchange (JSE) clawed back losses seen since Monday when South Africa went into new lockdown restrictions to curb the spread of the third wave of coronavirus.
But Thursday's rally was largely driven by a rise in the prices of gold and platinum, analysts said.
"Today was a precious metals miner rally," said Roy Topol, portfolio manager at Cratos, adding that a rise in the price of the two precious metals most often gives a boost to South African miners.
However, South Africa Inc. stocks -- stocks such as banks or financials that are dependent on the local economy -- continue to be subdued, hinting that investors are still worried about the impact of lockdown restrictions.
The benchmark all-share index closed up 0.46% to 66,556 points, while the blue-chip index of top 40 companies ended 0.52% to 60,477 points.
The mining index ended the day up 1.83% with the price of platinum up around 1% and gold prices a few basis points up.
In fixed income, yield on the benchmark 2030 instrument rose 7.5 basis points to 8.955%.
(Reporting by Olivia Kumwenda-Mtambo and Promit Mukherjee, Editing by William Maclean)
