Studies | about us | >> Resources

Periodic Table--Potassium

Potassium has three naturally occurring isotopes: 39K (93.3%),40K (0.01%) and 41K (6.7%). Naturally emerging 40Kdecays to secure 40Ar (11.2%) by electron capture and also by positronemission, and decays to steady 40Ca (88.8%) through negatron emission;40K has a half-life of 1.250 x 109 years. The decayof 40K to 40Ar is generally used as a method for datingrocks. The conventional K-Ar dating technique depends on the presumption thatthe rocks consisted of no argon at the moment of formation and that every thesubsequent radiogenic argon (i.e., 40Ar) to be quantitativelyretained, i.e., closed system. Minerals room dated by measure of theconcentration that potassium, and the quantity of radiogenic 40Arthat has accumulated. The minerals the are best suited for date includebiotite, muscovite, and also plutonic/high great metamorphic hornblende, andvolcanic feldspar; totality rock samples from volcanic flows and shallow instrusivescan likewise be date if they are unaltered (Faure, 1986). For a discussionof K-Ar dating watch Dalrymple and also Lanphere (1969), Faure (1986), and Dicken(1995).

Outside that dating, K isotopes have actually been used extensively in studiesof weathering (Moldan and Cerny, 1993); K isotope have also be offered fornutrient cycling studies because K is a macro-nutrient compelled for life.

You are watching: How many isotopes does potassium have

Source that text: This evaluation was assembled by Dan Snyder, primarilyfrom Faure (1986).

References • Dalrymple, G.B. And Lanphere, M.A. (1969). Potassium-Argon dating. W.H. Freeman, san Francisco, 258 p. • Dicken, A.P. (1995). Radiogenic Isotope Geology. Cambridge UniversityPress, brand-new York, 452 p. • Faure, G. (1986). "The K-Ar an approach of dating", in Principlesof Isotope Geology, second edition, man Wiley and also Sons, new York,pp. 66-92. • Hunziker, J. C. (1979). "Potassium argon dating", In: E. Jägerand J.C. Hunziker (Eds.), Lecutres in Isotope Geology, Springer-Verlag, Berlin. Pp. 52-76.

See more: What Is A Dime Piece Mean Ing Of "I Walk In Like A Dime Piece?"?

• Moldan, B. And Cerny, J. (Eds.)(1993). Biogeochemistry of small Catchments--ATool for environmental Research, clinical Committee on problems ofthe Environment, man Wiley and also Sons, new York. 419 p. Related Links
Periodic Table
Fundamentals of stable Isotope Geochemistry
General References
Isotope publications
Studies | about us | >> Resources Please call Carol kendall (ckendall
usgs.gov) for questions and also comments about this page. This web page was last changed in January 2004. Come the USGS house Page come the Water sources Information residence Page