The mixed berries I used were a frozen mix of blackberries, blueberries and raspberries.  I used ice cubes and frozen cranberries for extra cool-ness.  The original recipe comes from Taste of Home and used just raspberries instead of mixed berries.

Raspberry Iced Tea
Adapted from Taste of Home
Makes 4 quarts

Ingredients
4 quarts water
1 1/2 cups sugar
1 package (12 ounces) frozen unsweetened raspberries
10 individual tea bags
1/4 cup lemon juice

Method
In a Dutch oven, bring water and sugar to a boil.  Remove from the heat; stir until sugar is dissolved.  Add the raspberries, tea bags and lemon juice.  Cover and steep for 3 minutes.

Strain; discard berries and tea bags.  Refrigerate until chilled.  Serve over ice.