“This place is going to be a gold mine, and my prediction is it’s going to branch and grow.” Just look at a map – and think about all that cash they’re supposed to spend on food and books and stuff,” said Scott Orr, 20, a Syracuse University junior who last month was on his third trip to the casino in two weeks. “I think a lot of business will come from students. As a result, the casino, 35 miles east of Syracuse, is quickly catching on with students from two dozen nearby colleges. The minimum age for casino gambling in most places, including Atlantic City and the Foxwoods casino in Ledyard, Conn., is 21. Few noticed that Turning Stone was also the only casino on the Eastern Seaboard where teen-agers could place bets. When the Oneida Indians opened the Turning Stone casino here in July, it was heralded as the first legal casino in New York state since the 1870s.