Also called crystal rock, translucent, colorless or hyaline, the crystal quartz was the first known crystal. The ancient Greeks named this stone clear as the water "krustallos ice", thinking that it was ice that was no longer melting. This stone propagates a pure and powerful energy. Useful for settling multiple daily worries, it brings positive energy, clarity of mind and rid its bearer of negative energies. In terms of health, it is effective for glands, for all problems related to the digestive tract, for back pain. It strengthens the eyes, the heart, the blood and lymphatic circulation as well as the lungs and nervous system.