Potassium 40 is useful for radioactive dating
{"Image DocumentName": "Radioisotopes commonly used for radiometric dating", "Image ImageDescription": "Carbon-14 (5730 years)\u2192 Nitrogen-14. Potassium-40 (1.3 billion years)\u2192 Argon-40. Rubidium-86 (18.66 days) \u2192 Strontium. Uranium-238 (4.5 billion years) \u2192 Lead.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}