Hot stone massage is a variation on classic massage therapy. Heated smooth, flat stones are placed on key points on the body. The massage therapist may also hold the stones and use them to massage certain areas of the body. The use of hot stones for healing dates back to ancient times, but it wasn't until Arizona introduced a hot stone massage technique, called LaStone Therapy, that the use of hot stones for massage caught on. The hot stones are usually made of basalt, a type of rock that is rich in iron, so they retain heat. River rocks are normally used because they are so smooth - they have been smoothed over time by the river's current.