1) In a 4-cup glass measure, combine together the 1 cup prepared lemonade and mint leaves. Store the remaining lemonade for future uses.
2) Microwave the lemonade mixture on HIGH, uncovered, for 2 to 3 minutes, till thoroughly heated.
3) Let the mixture stand for 5 minutes and then add the pineapple juice. Stir well.
4) Cover the preparation and chill for a minimum of 2 hours and then strain.
5) Stir in the sparkling mineral water lightly.
6) In a glass of preferrece, put ice and serve the cooler over the ice. If preferred, garnish with fresh mint. Makes an excellent refreshment.