What mineral is primarily responsible for the hardness of teeth enamel?

Calcium phosphate

What civilization is credited with inventing democracy? Which NBA player wrote a children's book titled "The Wizenard Series"? Which scandal involved fraudulent railroad construction contracts during the administration of President Ulysses S. Grant? What was the scandal regarding weapon sales to Iran funding Contras in Nicaragua? Who was the notorious gangster behind the St. Valentine's Day Massacre in Chicago?