The following table lists ALL radioactive nuclei with a half-life greater than 1000 years. An element decays away below detectable levels in about ten to fifteen half-lives.


Isotope Half-life (yr) Rel. Abundance
Holmium-166m 1,200 none
Berkelium-247 1,380 none
Radium-226 1,600 trace
Molybdenum-93 4,000 none
Holmium-153 4,570 none
Curium-246 4,730 none
Carbon-14 5,730 trace
Plutonium-240 6,563 none
Thorium-229 7,340 none
Americium-243 7,370 none
Curium-245 8,500 none
Curium-250 9,000 none
Tin-126 10,000 none
Iodine-129 15,700 none
Niobium-94 20,300 none
Plutonium-239 24,110 none
Proactinium-231 32,760 trace
Lead-202 52,500 none
Lanthanium-137 60,000 none
Thorium-230 75,380 none
Nickel-59 76,000 none
Thorium-230 77,000 trace
Calcium-41 103,000 none
Neptunium-236 154,000 none
Uranium-233 159,200 none
Rhenium-186m 200,000 none
Technetium-99 211,000 none
Krypton-81 229,000 none
Uranium-234 245,500 trace
Chlorine-36 301,000 none
Curium-248 340,000 none
Bismuth-208 368,000 none
Plutonium-242 373,300 none
Aluminum-26 717,000 none
Selenium-79 1,130,000 none
Iron-60 1,500,000 none
Beryllium-10 1,510,000 none
Zircon-93 1,530,000 none
Curium-247 1,560,000 none
Gadolinium-150 1,790,000 none
Neptunium-237 2,144,000 none
Cesium-135 2,300,000 none
Technetium-96 2,600,000 none
Dysprosium-154 3,000,000 none
Bismuth-310m 3,040,000 none
Mietnerium-53 3,740,000 none
Technetium-98 4,200,000 none
Palladium-107 6,500,000 none
Hafnium-182 9,000,000 none
Lead-205 15,300,000 none
Curium-247 15,600,000 none
Uranium-236 23,420,000 none
Niobium-92 34,700,000 none
Plutonium-244 80,800,000 none
Samarium-146 103,000,000 none
Uranium-236 234,200,000 none
Uranium-235 703,800,000 rare
Potassium-40 1,280,000,000 rare
Uranium-238 4,468,000,000 common
Rubidium-87 4,750,000,000 common
Thorium-232 14,100,000,000 common
Lutetium-176 37,800,000,000 rare
Rhenium-187 43,500,000,000 common
Lanthanium-138 105,000,000,000 rare
Samarium-147 106,000,000,000 common
Platinum-190 650,000,000,000 rare
Tellurium-123 >1 x 10^13 rare
Osmium-184 >5.6 x 10^13 rare
Gadolinium-152 1.08 x 10^14 rare
Tantalum-180m >1.2 x 10^15 rare
Xenon-124 >1.6 x 10^14 rare
Indium-115 4.41 x 10^14 common
Zinc-70 >5 x 10^14 rare
Hafnium-174 2.0 x 10^15 rare
Osmium-186 2.0 x 10^15 common
Samarium-149 >2 x 10^15 common
Neodymium-144 2.29 x 10^15 common
Samarium-148 7 x 10^15 common
Cadmium-113 7.7 x 10^15 common
Cerium-142 >5 x 10^16 common
Tungsten-183 >1.1 x 10^17 common
Vanadium-50 1.4 x 10^17 rare
Lead-204 1.4 x 10^17 common
Chromium-50 >1.8 x 10^17 common
Tungsten-184 >3 x 10^17 common
Calcium-48 >6.3 x 10^18 common
Molybdenum-100 1.0 x 10^19 common
Neodynium-150 >1.1 x 10^19 common
Zircon-96 >3.8 x 10^19 common
Selenium-82 1.1 x 10^20 common
Tellurium-130 7.9 x 10^20 common
Xenon-136 >2.4 x 10^21 common
Tellurium-128 2.2 x 10^24 common
Stable Isotopes infinite **

* "Common" means the isotope comprises more than 1% of the local atomic abundance of its element. "Rare" means it has an abundance of less than 1%. "Trace" means the elements concentration is effectively negligible, much less than 0.01%. In the case of Protactinium (whose only isotope is radioactive and short-lived) the concentration was compared to that of nearby elements.

**Of 280 total stable isotopes, about 70% are common, 30% are rare, and 1% are trace. NO stable isotopes are absent.)

Sources:
http://ie.lbl.gov/toi/nucSearch.asp
http://www.webelements.com/
http://www.blackcatsystems.com/science/natRadiation.html
Serway et al. 1997, "Modern Physics"