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The dates indicate the true age of the minerals only if the rocks have not been subsequently altered. See rubidium–strontium dating for a more detailed discussion. Other than 87 Rb, the longest-lived radioisotopes are 83 Rb with a half-life of 86.2 days, 84 Rb with a half-life of 33.1 days, and 86 Rb with a half-life of 18.642 days. All other ...
Commercial rubidium clocks are less accurate than caesium atomic clocks, which serve as primary frequency standards, so a rubidium clock is usually used as a secondary frequency standard. Commercial rubidium frequency standards operate by disciplining a crystal oscillator to the rubidium hyperfine transition of 6.8 GHz (6 834 682 610.904 Hz).
Low phosphate levels are an important limit to growth in a number of plant ecosystems. The vast majority of phosphorus compounds mined are consumed as fertilisers. Phosphate is needed to replace the phosphorus that plants remove from the soil, and its annual demand is rising nearly twice as fast as the growth of the human population.
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid, a.k.a. phosphoric acid H 3 PO 4. The phosphate or orthophosphate ion [PO 4] 3− is derived from phosphoric acid by the removal of three protons H +.
The body responds to the influx of dietary potassium, which raises serum potassium levels, by shifting potassium from outside to inside cells and increasing potassium excretion by the kidneys. Most industrial applications of potassium exploit the high solubility of its compounds in water, such as saltwater soap. Heavy crop production rapidly ...
Uranium is a naturally occurring element found in low levels in all rock, soil, and water. It is the highest-numbered element found naturally in significant quantities on Earth and is almost always found combined with other elements. [ 12 ]
Xenotime, a REE phosphate, is the main HREE ore containing as much as 60% yttrium as yttrium phosphate (YPO 4). [56] This applies to xenotime-(Y). [ 61 ] [ 64 ] [ 60 ] The largest mine is the Bayan Obo deposit in China, making China the largest exporter for HREE since the closure of the Mountain Pass mine in the 1990s.
Historically responsible for high metal levels in the Derwent River, [121] the zinc works at Lutana is the largest exporter in Tasmania, generating 2.5% of the state's GDP, and producing more than 250,000 tonnes of zinc per year.