To make 8 servings:
In a large pitcher combine 64 large mint leaves; 2 cups fresh blueberries; 2 limes, cut into quarters; and 2/3 cup superfine granulated sugar. Using a muddler or the back of a wooden spoon, mash ingredients together well, making sure most of the sugar is dissolved. Add 1 1/2 cups light rum and 4 cups chilled club soda. Stir to combine. Fill eight tall glasses with ice. Pour mojito into ice-filled glasses. If desired, garnish with mint springs. Serve immediately.