Pineapple and Peach Jam with Mint

• 1 (3½-pound) pineapple, washed, peel and eyes removed, quartered, and cored
• 1½ pounds

Prepare for water-bath canning: Sterilize the jars and keep them hot in the canning pot, put a small plate in the freezer, and put the flat lids in a heatproof bowl. (details.)

Cut the pineapple quarters lengthwise into 4 strips, then thinly slice; you should have about 4 cups.

Put the pineapple, peaches, and sugar in a wide,