Pitchblende dating

Planet Uranus) Yellow-colored glass, containing more than 1% uranium oxide and dating back to 79 A.D., has been found near Naples, Italy. Klaproth recognized an unknown element in pitchblende and attempted to isolate the metal in 1789. 

Were all of these newly discovered substances also new elements This question would not be answered for some years but there was a flurry of other major discoveries to keep the protagonists occupied. Pierre Curie discovered that radioactivity released large quantities of heat (Curie and Laborde 1903) which appeared mysterious—as if the heat was coming from nowhere. This discovery provided an extra heat source for the Earth and reconciled the estimates of a very old Earth, based on geological estimates, with the young age calculated by Lord Kelvin from cooling rates. The year 1903 also witnessed the first demonstration that a-decay released He (Ramsay and Soddy 1903). The build up of He was soon put to use to date geological materials, initially by Rutherford in 1905 who calculated the first ever radiometric age of 500 Myr for a pitchblende sample, and then by Strutt who examined a wide variety of minerals (Strutt... 

Chromite. In a letter to Scherers Journal, dated St. Petersburg, November 12, 1798, Count Musin-Pushkin wrote You already know that Mr. Lowitz and Mr. Klaproth have independently discovered chromium combined with iron in a fossil I sent them. This ore looks like the black uranium ore (pitchblende), but has a more metallic luster ... 

Lord Rutherford [24] determined the age of a sample of pitchblende, to be 700 million years, by measuring the amount of uranium and radium and helium retained in the rock and by calculating the annual output of alpha particles. The oldest rock found is from Southwest Greenland 3.8 Gyr old [15]. Radioactive dating of meteorites point to their formation and the solidification of the earth about 4.55 0.07 years ago [25]. Since the sun and the solar system formed only slightly before, their age at isolation and condensation from the interstellar medium is taken to be 4.6 Gyr [26]. 

The use of uranium, in its natural oxide form, dates back to at least 79 A.D., when it was used to add color to ceramic glazes.The German chemist Martin Klaproth is credited with discovering uranium in samples of the mineral pitchblende in 1789. It was first isolated as a metal in 1841 by Eugene-Melchior Peligot. Uranium was discovered to be radioactive by French physicist Henri Becquerel in 1896, who first discovered the process of radioactivity with uranium minerals. 

Uranium occurs in most phosphate rocks, but its concentration varies from deposit to deposit. Some sedimentary rocks show notably higher concentrations than most igneous rocks. The most uranium-rich rocks found to date are those of Florida (up to 300 ppmw U), Morocco (up to 230 ppmw U), and Jordan (up to 240 ppmw U) [32,33[. In comparison, conventional uranium deposits such as pitchblende typically have a uranium content of 1,000-3,000 ppmw. When the phosphate rock is acidulated, up to 80% or 90% of the ur ium passes into solution in the phosphoric add. The exact amount of PR acidulated depends on its characteristics and the parameters of the phosphoric acid process employed. Examples of the uranium contents of different phosphate rocks and of phosphoric acids produced from them are indicated in Table 11.29. 

To date, only a small number of deposits are known in Europe in Triassic sandstones the only notable prospect is located at Mazarate in the Guadalajara Province of Spain. Mineralization occurs in Lower Triassic red arkosic sandstones rich in volcanic debris and organic matter. Uranium appears as pitchblende and sooty pitchblende in reduced facies. 

---