TOKYO, Aug. 16 (Xinhua) -- Tokyo stocks opened lower Thursday as the yen's appreciation against the U.S. dollar coupled with Wall Street's overnight decline dented investor sentiment, amid ongoing concerns about heightening tensions between Turkey and the United States.

As of 9:15 a.m., the 225-issue Nikkei Stock Average dropped 296.72 points, or 1.34 percent, from Wednesday to 21,907.50.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, fell 28.06 points, or 1.65 percent, at 1,669.97.

Oil and coal product, mining and nonferrous metal-oriented issues comprised those that declined the most in the opening minutes after the morning bell.